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Fund (“Total International Index Fund” or the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“Fund”), a series of BlackRock Funds III (the “Trust”), is to match the performance of the MSCI All Country World Index </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">ex USA Index (the “MSCI ACWI ex USA Index” or the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Underlying Index</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">) in U.S. dollars with net dividends as closely as </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">possible before the deduction of Fund expenses.</span></div> Fees and Expenses of the Fund <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Total International </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index Fund. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">You may pay other fees, such as brokerage commissions and other fees to your financial professional or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">your selected securities dealer, broker, investment adviser, service provider or industry professional (including </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">BlackRock Fund Advisors (</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">BFA</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">) and its affiliates) (each, a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">Financial Intermediary</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">), which are not reflected in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">the table and example below.</span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)1 0.0003 0.0003 0.0025 0 0.0012 0.0011 0.0001 0.0001 0.0010 0.0009 0.0001 0.0001 0.0040 0.0014 0.0040 0.0014 June 30, 2027 Example: <div style="line-height: 10.695pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or lower, based on these assumptions your costs would be:</span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> 41 128 224 505 14 45 79 179 Portfolio Turnover: <div style="line-height: 10.695pt; margin-top: 0.0pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Master Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Example, affect the Fund’s performance. During the most recent fiscal year, the Master Portfolio’s portfolio turnover </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">rate was </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">13</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">% of the average value of its portfolio.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> 0.13 Principal Investment Strategies of the Fund <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Total International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">assets whose performance is expected to match approximately the performance of the MSCI ACWI ex USA Index. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund will be substantially invested in equity securities in the MSCI ACWI ex USA Index, and will invest, under normal </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">circumstances, at least 80% of its net assets in securities or other financial instruments that are components of or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">have economic characteristics similar to the securities included in the MSCI ACWI ex USA Index. Equity securities in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">which the Fund invests consist primarily of common stock, preferred stock and securities or other instruments whose </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">price is linked to the value of common stock.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund will invest in the common stocks represented in the MSCI ACWI ex USA Index in roughly the same </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">proportions as their weightings in the MSCI ACWI ex USA Index. The MSCI ACWI ex USA Index is a free float-adjusted </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">market capitalization index that captures large and mid cap representation across 22 of 23 developed markets </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">countries (excluding the United States) and 24 emerging markets countries. With 1,977 constituents, the index covers </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">approximately 85% of the global equity opportunity set outside the United States. The component stocks have a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">market capitalization between $172.53 million and $1.36 trillion as of March 31, 2026. The Fund may also engage in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">futures transactions. At times, the Fund may not invest in all of the common stocks in the MSCI ACWI ex USA Index, or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">in the same weightings as in the MSCI ACWI ex USA Index. At those times, the Fund chooses investments so that the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">market capitalizations, industry weightings and other fundamental characteristics of the stocks chosen are similar to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the MSCI ACWI ex USA Index as a whole. The Fund may lend securities with a value up to 33</span><span style="color: #000000; font-family: arial; font-size: 6pt; position: relative; top: -2.66pt;"> 1</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">∕</span><span style="color: #000000; font-family: arial; font-size: 6pt;">3</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">% of its total assets to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">financial institutions that provide cash or securities issued or guaranteed by the U.S. Government as collateral. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">industries to approximately the same extent that the MSCI ACWI ex USA Index is concentrated.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund is a “feeder” fund that invests all of its assets in the Master Portfolio, which has the same investment </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">objective and strategies as the Fund. All investments are made at the Master Portfolio level. This structure is </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investment results of the Master Portfolio. For simplicity, this prospectus uses the name of the Fund or the term </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“Fund” (as applicable) to include the Master Portfolio.</span></div> You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Concentration Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund reserves the right to concentrate its investments (i.e., invest 25% or more of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">total assets in securities of issuers in a particular industry) to approximately the same extent that the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index concentrates in a particular industry. To the extent the Fund concentrates in a particular industry, it may be </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">more susceptible to economic conditions and risks affecting that industry.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Emerging Markets Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Emerging markets are riskier than more developed markets because they tend to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div style="line-height: 10.695pt; margin-left: 12pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">returns to U.S. investors. In addition, many emerging financial markets have far lower trading volumes and less </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">liquidity than developed markets.</span></div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Equity Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Stock markets are volatile. The price of equity securities fluctuates based on changes in a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">company’s financial condition and overall market and economic conditions.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Foreign Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Foreign investments often involve special risks not present in U.S. investments that can </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">increase the chances that the Fund will lose money. These risks include:</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">oversight.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The economies of certain foreign markets may not compare favorably with the economy of the United States with </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">payments position.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The governments of certain countries, or the U.S. Government with respect to certain countries, may prohibit or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">impose substantial restrictions through capital controls and/or sanctions on foreign investments in the capital </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">markets or certain industries in those countries, which may prohibit or restrict the ability to own or transfer </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">currency, securities, derivatives or other assets.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the same extent as does the United States and may not have laws to protect investors that are comparable to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">U.S. securities laws.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities not typically associated with settlement and clearance of U.S. investments.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund’s claims to recover foreign withholding taxes may not be successful, and if the likelihood of recovery of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">foreign withholding taxes materially decreases, due to, for example, a change in tax regulation or approach in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">foreign country, accruals in the Fund’s net asset value for such refunds may be written down partially or in full, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">which will adversely affect the Fund’s net asset value.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The European financial markets have recently experienced volatility and adverse trends due to concerns about </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">economic downturns in, or rising government debt levels of, several European countries, as well as acts of war in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the region. These events may spread to other countries in Europe and may affect the value and liquidity of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">certain of the Fund’s investments.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Futures Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund’s use of futures may reduce the Fund’s returns. In these transactions, the Fund is </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">subject to liquidity risk and correlation risk (i.e., that fluctuations in a future’s value may not correlate with the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">change in market value of the instruments held by the Fund).</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Index-Related Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — The index provider may rely on various sources of information to assess the criteria of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">components of the underlying index, including information that may be based on assumptions and estimates. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Neither the Fund nor BlackRock can offer assurances that the index provider’s methodology or sources of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">information will provide an accurate assessment of included components. Errors in index data, index computations </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or the construction of the underlying index in accordance with its methodology may occur, and the index provider </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may not identify or correct them promptly or at all, which may have an adverse impact on the Fund and its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">shareholders. Unusual market conditions or other unforeseen circumstances (such as natural disasters, political </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">unrest or war) may impact the index provider or a third-party data provider and could cause the index provider to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">postpone a scheduled rebalance. This could cause the underlying index to vary from its normal or expected </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">composition.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Large-Capitalization Companies Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Large-capitalization companies may be less able than smaller-capitalization </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">companies to adapt to changing market conditions and competitive challenges. Large-capitalization companies may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">be more mature and subject to more limited growth potential compared with smaller-capitalization companies. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance of large-capitalization companies could trail the overall performance of the broader securities markets. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund performance depends on the performance of individual securities to which the Fund has exposure. Changes in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the financial condition or credit rating of an issuer of those securities may cause the value of the securities to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">decline.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Market Risk and Selection Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Market risk is the risk that one or more markets in which the Fund invests will </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">go down in value, including the possibility that the markets will go down sharply and unpredictably. The value of a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">security or other asset may decline due to changes in general market conditions, economic trends or events that </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div style="line-height: 10.695pt; margin-left: 12pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investments. Selection risk is the risk that the securities selected by Fund management will underperform the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">markets, the relevant indices or the securities selected by other funds with similar investment objectives and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investment strategies. This means you may lose money.</span></div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Mid Cap Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The securities of mid cap companies generally trade in lower volumes and are generally </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">subject to greater and less predictable price changes than the securities of larger capitalization companies.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Operational and Technology Risks </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The Fund is directly and indirectly susceptible to operational and technology </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">risks, including those related to human errors, processing errors, communication errors, systems failures, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">cybersecurity incidents, and the use of artificial intelligence and machine learning (</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">AI</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">), which may result in losses </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">for the Fund and its shareholders or may impair the Fund’s operations. While the Fund’s service providers are </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">required to have appropriate operational, information security and cybersecurity risk management policies and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">procedures, their methods of risk management may differ from those of the Fund. Operational and technology risks </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">for the issuers in which the Fund invests could also result in material adverse consequences for such issuers and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may cause the Fund’s investments in such issuers to lose value.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Passive Investment Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> Because BFA does not select individual companies in the index that the Fund tracks, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the Fund may hold securities of companies that present risks that an investment adviser researching individual </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities might seek to avoid.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Preferred Securities Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Preferred securities may pay fixed or adjustable rates of return. Preferred securities </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">preferred securities generally pay dividends only after the company makes required payments to holders of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">and other debt to actual or perceived changes in the company’s financial condition or prospects. Preferred </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities of smaller companies may be more vulnerable to adverse developments than preferred securities of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">larger companies.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Securities Lending Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — The Fund may engage in securities lending. Securities lending involves the risk that the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities or a decline in the value of any investments made with cash collateral. These events could also trigger </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">adverse tax consequences for the Fund.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Small Cap and Emerging Growth Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Small cap or emerging growth companies may have limited </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">product lines or markets. They may be less financially secure than larger, more established companies. They may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">depend on a more limited management group than larger capitalized companies.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Tracking Error Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund is subject to the risk of “tracking error,” which is the divergence of the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance from that of the Underlying Index. Tracking error may occur due to a number of factors, including </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">differences between the securities and other assets held in the Fund’s portfolio and those included in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Underlying Index; differences in the timing and methodologies used to value securities and other assets; </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">transaction costs and other expenses incurred by the Fund that the Underlying Index does not incur; the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">holding of uninvested cash; differences in the timing of the accrual or the valuation of dividends or interest received </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">by the Fund or distributions paid to Fund shareholders; tax gains or losses; differences between the amount and/or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">timing of withholding taxes on dividends reflected in the Underlying Index from the Fund’s obligation, if any, for </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">foreign withholding taxes; the requirements for the Fund to maintain pass-through tax treatment; portfolio </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">transactions carried out to minimize the distribution of capital gains to shareholders; changes to the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index, such as during a rebalancing or reconstitution; and impacts to the Fund of complying with certain regulatory </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">requirements or limits. A fund that tracks an index composed of a large number of securities or other assets may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">experience greater tracking error than a fund that tracks a more narrow index. Tracking error risk may be heightened </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">during times of increased market volatility or other unusual market conditions.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> Performance Information <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The information shows you how the performance of Total International Index Fund has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the MSCI ACWI ex USA Index (Net). To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. The table includes all applicable fees. If BFA, BAL and their affiliates had not waived or reimbursed certain Fund expenses during these </span></div> <div style="line-height: 10.695pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance, including its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">current net asset value, can be obtained by visiting www.blackrock.com or can be obtained by phone at </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">(800) 882-0052</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">.</span></div> The information shows you how the performance of Total International Index Fund has varied year by year and provides some indication of the risks of investing in the Fund. As with all such investments, past performance (before and after taxes) is not an indication of future results. www.blackrock.com (800) 882-0052 Investor A SharesANNUAL TOTAL RETURNSiShares MSCI Total International Index Fund As of 12/31 <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">During the ten-year period shown in the bar chart, the highest return for a quarter was 17.10% (quarter ended </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">June 30, 2020) and the lowest return for a quarter was -23.67% (quarter ended March 31, 2020).</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> highest return 0.1710 2020-06-30 lowest return -0.2367 2020-03-31 For the periods ended 12/31/25Average Annual Total Returns 0.3221 0.0737 0.0803 0.3136 0.0686 0.0751 0.1974 0.0582 0.0653 0.3258 0.0766 0.0831 0.3239 0.0791 0.0841 <div style="margin-top: 12pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Institutional Shares will vary. </span></div> After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Institutional Shares will vary Fund Overview Key Facts About iShares Russell 1000 Large-Cap Index Fund Investment Objective <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The investment objective of iShares Russell 1000 Large-Cap Index Fund (“Large-Cap Index Fund” or the “Fund”), a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">series of BlackRock Funds III (the “Trust”), is to match the performance of the Russell 1000</span><span style="color: #000000; font-family: arial; font-size: 5pt; position: relative; top: -3.25pt;">®</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> Index (the “Russell </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">1000” or the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Underlying Index</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">) as closely as possible before the deduction of Fund expenses.</span></div> Fees and Expenses of the Fund <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Large-Cap Index </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">You may pay other fees, such as brokerage commissions and other fees to your financial professional or your </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">selected securities dealer, broker, investment adviser, service provider or industry professional (including </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">BlackRock Fund Advisors (</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">BFA</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">) and its affiliates) (each, a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">Financial Intermediary</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">), which are not reflected in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">the table and example below.</span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> Annual Fund Operating Expenses(expenses that you pay each year as apercentage of the value of your investment)1 0.0003 0.0003 0.0025 0 0.0008 0.0008 0.0001 0.0001 0.0007 0.0007 0.0036 0.0011 0.0036 0.0011 June 30, 2027 Example: <div style="line-height: 10.695pt; margin-top: 0.0pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or lower, based on these assumptions your costs would be:</span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> 37 116 202 456 11 35 62 141 Portfolio Turnover: <div style="line-height: 10.695pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Master Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Master Portfolio’s portfolio turnover rate was 12% of the average value of its portfolio.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> 0.12 Principal Investment Strategies of the Fund <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Large-Cap Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">whose performance is expected to match approximately the performance of the Russell 1000. The Fund will be </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">substantially invested in equity securities in the Russell 1000, and will invest, under normal circumstances, at least </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">80% of its net assets in securities or other financial instruments that are components of or have economic </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">characteristics similar to the securities included in the Russell 1000. Equity securities in which the Fund invests </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">include common stock, preferred stock and securities or other instruments whose price is linked to the value of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">common stock.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund will invest in the common stocks represented in the Russell 1000 in roughly the same proportions as their </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">weightings in the Russell 1000. As of March 31, 2026, the companies in the Russell 1000 have a market </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">capitalization ranging from $134.5 billion to $4.32 trillion. The Fund may also engage in futures transactions. At times, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the Fund may not invest in all of the common stocks in the Russell 1000, or in the same weightings as in the Russell </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">1000. At those times, the Fund chooses investments so that the market capitalizations, industry weightings and other </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">fundamental characteristics of the stocks chosen are similar to the Russell 1000 as a whole. The Fund may lend </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities with a value up to 33</span><span style="color: #000000; font-family: arial; font-size: 6pt; position: relative; top: -2.66pt;"> 1</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">∕</span><span style="color: #000000; font-family: arial; font-size: 6pt;">3</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">% of its total assets to financial institutions that provide cash or securities issued or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">guaranteed by the U.S. Government as collateral. The Fund will concentrate its investments (i.e., hold 25% or more of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">its total assets) in a particular industry or group of industries to approximately the same extent that the Russell 1000 </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">is concentrated.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund is a “feeder” fund that invests all of its assets in the Master Portfolio, which has the same investment </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">objective and strategies as the Fund. All investments are made at the Master Portfolio level. This structure is </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investment results of the Master Portfolio. For simplicity, this prospectus uses the name of the Fund or the term </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“Fund” (as applicable) to include the Master Portfolio.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund intends to be diversified in approximately the same proportion as the Underlying Index is diversified. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund may become </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">non-diversified,</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> as defined in the Investment Company Act of 1940, as amended, solely as a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index. Shareholder approval will not be sought if the Fund becomes </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">non-diversified</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> due solely to a change in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">relative market capitalization or index weighting of one or more constituents of the Underlying Index.</span></div> You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Concentration Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund reserves the right to concentrate its investments (i.e., invest 25% or more of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">total assets in securities of issuers in a particular industry) to approximately the same extent that the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index concentrates in a particular industry. To the extent the Fund concentrates in a particular industry, it may be </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">more susceptible to economic conditions and risks affecting that industry.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Equity Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Stock markets are volatile. The price of equity securities fluctuates based on changes in a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">company’s financial condition and overall market and economic conditions.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Information Technology Sector Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— IT companies face intense competition, both domestically and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">internationally, which may have an adverse effect on their profit margins. Like other technology companies, IT </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">companies may have limited product lines, markets, financial resources or personnel. The products of IT companies </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may face obsolescence due to rapid technological developments, frequent new product introduction, unpredictable </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div style="line-height: 10.695pt; margin-left: 12pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">changes in growth rates and competition for the services of qualified personnel. Companies in the IT sector are </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">heavily dependent on patent and intellectual property rights. The loss or impairment of these rights may adversely </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">affect the profitability of these companies. Companies in the IT sector may face increased government and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">regulatory scrutiny and may be subject to adverse government or regulatory action. Companies in the application </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">software industry, in particular, may also be negatively affected by the decline or fluctuation of subscription renewal </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">rates for their products and services, which may have an adverse effect on profit margins. Companies in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">systems software industry may be adversely affected by, among other things, actual or perceived security </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">vulnerabilities in their products and services, which may result in individual or class action lawsuits, state or federal </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">enforcement actions and other remediation costs.</span></div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Futures Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund’s use of futures may reduce the Fund’s returns. In these transactions, the Fund is </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">subject to liquidity risk and correlation risk (i.e., that fluctuations in a future’s value may not correlate with the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">change in market value of the instruments held by the Fund).</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Index-Related Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — The index provider may rely on various sources of information to assess the criteria of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">components of the underlying index, including information that may be based on assumptions and estimates. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Neither the Fund nor BlackRock can offer assurances that the index provider’s methodology or sources of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">information will provide an accurate assessment of included components. Errors in index data, index computations </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or the construction of the underlying index in accordance with its methodology may occur, and the index provider </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may not identify or correct them promptly or at all, which may have an adverse impact on the Fund and its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">shareholders. Unusual market conditions or other unforeseen circumstances (such as natural disasters, political </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">unrest or war) may impact the index provider or a third-party data provider and could cause the index provider to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">postpone a scheduled rebalance. This could cause the underlying index to vary from its normal or expected </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">composition.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Large-Capitalization Companies Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Large-capitalization companies may be less able than smaller-capitalization </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">companies to adapt to changing market conditions and competitive challenges. Large-capitalization companies may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">be more mature and subject to more limited growth potential compared with smaller-capitalization companies. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance of large-capitalization companies could trail the overall performance of the broader securities markets. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund performance depends on the performance of individual securities to which the Fund has exposure. Changes in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the financial condition or credit rating of an issuer of those securities may cause the value of the securities to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">decline.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Market Risk and Selection Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Market risk is the risk that one or more markets in which the Fund invests will </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">go down in value, including the possibility that the markets will go down sharply and unpredictably. The value of a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">security or other asset may decline due to changes in general market conditions, economic trends or events that </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investments. Selection risk is the risk that the securities selected by Fund management will underperform the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">markets, the relevant indices or the securities selected by other funds with similar investment objectives and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investment strategies. This means you may lose money.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Mid Cap Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The securities of mid cap companies generally trade in lower volumes and are generally </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">subject to greater and less predictable price changes than the securities of larger capitalization companies.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Non</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">-Diversification Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;"> —</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> To the extent the Fund is non-diversified, the Fund may invest a large percentage of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">assets in securities or other instruments representing a small number of issuers or counterparties and thus may be </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">more susceptible to the risks associated with these particular issuers or counterparties. As a result, the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance may depend to a greater extent on the performance of a small number of issuers or counterparties, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">which may lead to more volatility in the Fund’s net asset value.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Operational and Technology Risks </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The Fund is directly and indirectly susceptible to operational and technology </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">risks, including those related to human errors, processing errors, communication errors, systems failures, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">cybersecurity incidents, and the use of artificial intelligence and machine learning (</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">AI</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">), which may result in losses </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">for the Fund and its shareholders or may impair the Fund’s operations. While the Fund’s service providers are </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">required to have appropriate operational, information security and cybersecurity risk management policies and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">procedures, their methods of risk management may differ from those of the Fund. Operational and technology risks </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">for the issuers in which the Fund invests could also result in material adverse consequences for such issuers and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may cause the Fund’s investments in such issuers to lose value.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Passive Investment Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> Because BFA does not select individual companies in the index that the Fund tracks, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the Fund may hold securities of companies that present risks that an investment adviser researching individual </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities might seek to avoid.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Preferred Securities Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Preferred securities may pay fixed or adjustable rates of return. Preferred securities </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">preferred securities generally pay dividends only after the company makes required payments to holders of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">and other debt to actual or perceived changes in the company’s financial condition or prospects. Preferred </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities of smaller companies may be more vulnerable to adverse developments than preferred securities of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">larger companies.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Securities Lending Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — The Fund may engage in securities lending. Securities lending involves the risk that the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities or a decline in the value of any investments made with cash collateral. These events could also trigger </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">adverse tax consequences for the Fund.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Tracking Error Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund is subject to the risk of “tracking error,” which is the divergence of the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance from that of the Underlying Index. Tracking error may occur due to a number of factors, including </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">differences between the securities and other assets held in the Fund’s portfolio and those included in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Underlying Index; differences in the timing and methodologies used to value securities and other assets; </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">transaction costs and other expenses incurred by the Fund that the Underlying Index does not incur; the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">holding of uninvested cash; differences in the timing of the accrual or the valuation of dividends or interest received </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">by the Fund or distributions paid to Fund shareholders; tax gains or losses; differences between the amount and/or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">timing of withholding taxes on dividends reflected in the Underlying Index from the Fund’s obligation, if any, for </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">foreign withholding taxes; the requirements for the Fund to maintain pass-through tax treatment; portfolio </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">transactions carried out to minimize the distribution of capital gains to shareholders; changes to the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index, such as during a rebalancing or reconstitution; and impacts to the Fund of complying with certain regulatory </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">requirements or limits. A fund that tracks an index composed of a large number of securities or other assets may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">experience greater tracking error than a fund that tracks a more narrow index. Tracking error risk may be heightened </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">during times of increased market volatility or other unusual market conditions.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> Performance Information <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The information shows you how the performance of Large-Cap Index Fund has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell 1000. To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. The table includes all applicable fees. If BFA, BAL and their affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance, including its current net asset value, can be obtained by visiting www.blackrock.com or can be obtained by phone at (800) 882-0052. </span></div> The information shows you how the performance of Large-Cap Index Fund has varied year by year and provides some indication of the risks of investing in the Fund. As with all such investments, past performance (before and after taxes) is not an indication of future results. www.blackrock.com (800) 882-0052 Investor A SharesANNUAL TOTAL RETURNSiShares Russell 1000 Large-Cap Index FundAs of 12/31 <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">During the ten-year period shown in the bar chart, the highest return for a quarter was 21.65% (quarter ended </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">June 30, 2020) and the lowest return for a quarter was -20.29% (quarter ended March 31, 2020).</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> highest return 0.2165 2020-06-30 lowest return -0.2029 2020-03-31 For the periods ended 12/31/25Average Annual Total Returns 0.1694 0.1320 0.1416 0.1614 0.1265 0.1349 0.1041 0.1039 0.1164 0.1721 0.1348 0.1446 0.1737 0.1359 0.1459 <div style="margin-top: 12pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Institutional Shares will vary.</span></div> After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Institutional Shares will vary. Fund Overview Key Facts About iShares MSCI Total International Index Fund Investment Objective <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The investment objective of iShares MSCI Total International Index Fund (“Total International Index Fund” or the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“Fund”), a series of BlackRock Funds III (the “Trust”), is to match the performance of the MSCI All Country World Index </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">ex USA Index (the “MSCI ACWI ex USA Index” or the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Underlying Index</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">) in U.S. dollars with net dividends as closely as </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">possible before the deduction of Fund expenses.</span></div> Fees and Expenses of the Fund <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">This table describes the fees and expenses that you may pay if you buy, hold and sell Class K Shares of the Total </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">International Index Fund. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">You may pay other fees, such as brokerage commissions and other fees to your financial </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">professional or your selected securities dealer, broker, investment adviser, service provider or industry professional </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">(including BlackRock Fund Advisors (</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">BFA</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">) and its affiliates) (each, a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">Financial Intermediary</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">), which are not </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">reflected in the table and example below.</span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)1 0.0003 0 0.0006 0.0001 0.0004 0.0001 0.0009 0.0009 June 30, 2027 Example: <div style="line-height: 10.695pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or lower, based on these assumptions your costs would be:</span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> 9 29 51 115 Portfolio Turnover: <div style="line-height: 10.695pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Master Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Example, affect the Fund’s performance. During the most recent fiscal year, the Master Portfolio’s portfolio turnover </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">rate was </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">13</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">% of the average value of its portfolio.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> 0.13 Principal Investment Strategies of the Fund <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Total International Index Fund employs a “passive” management approach, attempting to invest in a portfolio of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">assets whose performance is expected to match approximately the performance of the MSCI ACWI ex USA Index. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund will be substantially invested in equity securities in the MSCI ACWI ex USA Index, and will invest, under normal </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">circumstances, at least 80% of its net assets in securities or other financial instruments that are components of or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">have economic characteristics similar to the securities included in the MSCI ACWI ex USA Index. Equity securities in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">which the Fund invests consist primarily of common stock, preferred stock and securities or other instruments whose </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">price is linked to the value of common stock.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund will invest in the common stocks represented in the MSCI ACWI ex USA Index in roughly the same </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">proportions as their weightings in the MSCI ACWI ex USA Index. The MSCI ACWI ex USA Index is a free float-adjusted </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">market capitalization index that captures large and mid cap representation across 22 of 23 developed markets </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">countries (excluding the United States) and 24 emerging markets countries. With 1,977 constituents, the index covers </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">approximately 85% of the global equity opportunity set outside the United States. The component stocks have a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">market capitalization between $172.53 million and $1.36 trillion as of March 31, 2026. The Fund may also engage in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">futures transactions. At times, the Fund may not invest in all of the common stocks in the MSCI ACWI ex USA Index, or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">in the same weightings as in the MSCI ACWI ex USA Index. At those times, the Fund chooses investments so that the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">market capitalizations, industry weightings and other fundamental characteristics of the stocks chosen are similar to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the MSCI ACWI ex USA Index as a whole. The Fund may lend securities with a value up to 33</span><span style="color: #000000; font-family: arial; font-size: 6pt; position: relative; top: -2.66pt;"> 1</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">∕</span><span style="color: #000000; font-family: arial; font-size: 6pt;">3</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">% of its total assets to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">financial institutions that provide cash or securities issued or guaranteed by the U.S. Government as collateral. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">industries to approximately the same extent that the MSCI ACWI ex USA Index is concentrated.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund is a “feeder” fund that invests all of its assets in the Master Portfolio, which has the same investment </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">objective and strategies as the Fund. All investments are made at the Master Portfolio level. This structure is </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investment results of the Master Portfolio. For simplicity, this prospectus uses the name of the Fund or the term </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“Fund” (as applicable) to include the Master Portfolio.</span></div> You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Concentration Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund reserves the right to concentrate its investments (i.e., invest 25% or more of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">total assets in securities of issuers in a particular industry) to approximately the same extent that the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index concentrates in a particular industry. To the extent the Fund concentrates in a particular industry, it may be </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">more susceptible to economic conditions and risks affecting that industry.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Emerging Markets Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Emerging markets are riskier than more developed markets because they tend to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">returns to U.S. investors. In addition, many emerging financial markets have far lower trading volumes and less </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">liquidity than developed markets.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Equity Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Stock markets are volatile. The price of equity securities fluctuates based on changes in a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">company’s financial condition and overall market and economic conditions.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Foreign Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Foreign investments often involve special risks not present in U.S. investments that can </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">increase the chances that the Fund will lose money. These risks include:</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">oversight.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The economies of certain foreign markets may not compare favorably with the economy of the United States with </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">payments position.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The governments of certain countries, or the U.S. Government with respect to certain countries, may prohibit or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">impose substantial restrictions through capital controls and/or sanctions on foreign investments in the capital </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">markets or certain industries in those countries, which may prohibit or restrict the ability to own or transfer </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">currency, securities, derivatives or other assets.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the same extent as does the United States and may not have laws to protect investors that are comparable to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">U.S. securities laws.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities not typically associated with settlement and clearance of U.S. investments.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund’s claims to recover foreign withholding taxes may not be successful, and if the likelihood of recovery of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">foreign withholding taxes materially decreases, due to, for example, a change in tax regulation or approach in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">foreign country, accruals in the Fund’s net asset value for such refunds may be written down partially or in full, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">which will adversely affect the Fund’s net asset value.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; margin-left: 12pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 493.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The European financial markets have recently experienced volatility and adverse trends due to concerns about </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">economic downturns in, or rising government debt levels of, several European countries, as well as acts of war in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the region. These events may spread to other countries in Europe and may affect the value and liquidity of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">certain of the Fund’s investments.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Futures Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund’s use of futures may reduce the Fund’s returns. In these transactions, the Fund is </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">subject to liquidity risk and correlation risk (i.e., that fluctuations in a future’s value may not correlate with the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">change in market value of the instruments held by the Fund).</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Index-Related Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — The index provider may rely on various sources of information to assess the criteria of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">components of the underlying index, including information that may be based on assumptions and estimates. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Neither the Fund nor BlackRock can offer assurances that the index provider’s methodology or sources of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">information will provide an accurate assessment of included components. Errors in index data, index computations </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or the construction of the underlying index in accordance with its methodology may occur, and the index provider </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may not identify or correct them promptly or at all, which may have an adverse impact on the Fund and its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">shareholders. Unusual market conditions or other unforeseen circumstances (such as natural disasters, political </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">unrest or war) may impact the index provider or a third-party data provider and could cause the index provider to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">postpone a scheduled rebalance. This could cause the underlying index to vary from its normal or expected </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">composition.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Large-Capitalization Companies Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Large-capitalization companies may be less able than smaller-capitalization </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">companies to adapt to changing market conditions and competitive challenges. Large-capitalization companies may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">be more mature and subject to more limited growth potential compared with smaller-capitalization companies. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance of large-capitalization companies could trail the overall performance of the broader securities markets. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund performance depends on the performance of individual securities to which the Fund has exposure. Changes in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the financial condition or credit rating of an issuer of those securities may cause the value of the securities to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">decline.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Market Risk and Selection Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Market risk is the risk that one or more markets in which the Fund invests will </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">go down in value, including the possibility that the markets will go down sharply and unpredictably. The value of a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">security or other asset may decline due to changes in general market conditions, economic trends or events that </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investments. Selection risk is the risk that the securities selected by Fund management will underperform the </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div style="line-height: 10.695pt; margin-left: 12pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">markets, the relevant indices or the securities selected by other funds with similar investment objectives and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investment strategies. This means you may lose money.</span></div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Mid Cap Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The securities of mid cap companies generally trade in lower volumes and are generally </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">subject to greater and less predictable price changes than the securities of larger capitalization companies.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Operational and Technology Risks </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The Fund is directly and indirectly susceptible to operational and technology </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">risks, including those related to human errors, processing errors, communication errors, systems failures, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">cybersecurity incidents, and the use of artificial intelligence and machine learning (</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">AI</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">), which may result in losses </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">for the Fund and its shareholders or may impair the Fund’s operations. While the Fund’s service providers are </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">required to have appropriate operational, information security and cybersecurity risk management policies and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">procedures, their methods of risk management may differ from those of the Fund. Operational and technology risks </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">for the issuers in which the Fund invests could also result in material adverse consequences for such issuers and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may cause the Fund’s investments in such issuers to lose value.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Passive Investment Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> Because BFA does not select individual companies in the index that the Fund tracks, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the Fund may hold securities of companies that present risks that an investment adviser researching individual </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities might seek to avoid.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Preferred Securities Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Preferred securities may pay fixed or adjustable rates of return. Preferred securities </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">preferred securities generally pay dividends only after the company makes required payments to holders of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">and other debt to actual or perceived changes in the company’s financial condition or prospects. Preferred </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities of smaller companies may be more vulnerable to adverse developments than preferred securities of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">larger companies.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Securities Lending Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — The Fund may engage in securities lending. Securities lending involves the risk that the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities or a decline in the value of any investments made with cash collateral. These events could also trigger </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">adverse tax consequences for the Fund.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Small Cap and Emerging Growth Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Small cap or emerging growth companies may have limited </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">product lines or markets. They may be less financially secure than larger, more established companies. They may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">depend on a more limited management group than larger capitalized companies.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Tracking Error Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund is subject to the risk of “tracking error,” which is the divergence of the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance from that of the Underlying Index. Tracking error may occur due to a number of factors, including </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">differences between the securities and other assets held in the Fund’s portfolio and those included in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Underlying Index; differences in the timing and methodologies used to value securities and other assets; </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">transaction costs and other expenses incurred by the Fund that the Underlying Index does not incur; the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">holding of uninvested cash; differences in the timing of the accrual or the valuation of dividends or interest received </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">by the Fund or distributions paid to Fund shareholders; tax gains or losses; differences between the amount and/or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">timing of withholding taxes on dividends reflected in the Underlying Index from the Fund’s obligation, if any, for </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">foreign withholding taxes; the requirements for the Fund to maintain pass-through tax treatment; portfolio </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">transactions carried out to minimize the distribution of capital gains to shareholders; changes to the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index, such as during a rebalancing or reconstitution; and impacts to the Fund of complying with certain regulatory </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">requirements or limits. A fund that tracks an index composed of a large number of securities or other assets may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">experience greater tracking error than a fund that tracks a more narrow index. Tracking error risk may be heightened </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">during times of increased market volatility or other unusual market conditions.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> Performance Information <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The information shows you how the performance of Total International Index Fund has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the MSCI ACWI ex USA Index (Net). To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. The table includes all applicable fees. If BFA, BAL and their affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance, including its current net asset value, can be obtained by visiting www.blackrock.com or can be obtained by phone at (800) 882-0052.</span></div> The information shows you how the performance of Total International Index Fund has varied year by year and provides some indication of the risks of investing in the Fund. As with all such investments, past performance (before and after taxes) is not an indication of future results. www.blackrock.com (800) 882-0052 Class K Shares ANNUAL TOTAL RETURNS iShares MSCI Total International Index Fund As of 12/31 <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">During the ten-year period shown in the bar chart, the highest return for a quarter was 17.16% (quarter ended June 30, 2020) and the lowest return for a quarter was -23.64% (quarter ended March 31, 2020).</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> highest return 0.1716 2020-06-30 lowest return -0.2364 2020-03-31 For the periods ended 12/31/25Average Annual Total Returns 0.3257 0.0771 0.0836 0.3166 0.0710 0.0776 0.1999 0.0605 0.0677 0.3239 0.0791 0.0841 <div style="margin-top: 12pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. Fund Overview Key Facts About iShares Russell 1000 Large-Cap Index Fund Investment Objective <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The investment objective of iShares Russell 1000 Large-Cap Index Fund (“Large-Cap Index Fund” or the “Fund”), a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">series of BlackRock Funds III (the “Trust”), is to match the performance of the Russell 1000</span><span style="color: #000000; font-family: arial; font-size: 5pt; position: relative; top: -3.25pt;">®</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> Index (the “Russell </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">1000” or the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Underlying Index</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">) as closely as possible before the deduction of Fund expenses.</span></div> Fees and Expenses of the Fund <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">This table describes the fees and expenses that you may pay if you buy, hold and sell Class K Shares of the Large-Cap </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index Fund. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">You may pay other fees, such as brokerage commissions and other fees to your financial professional or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">your selected securities dealer, broker, investment adviser, service provider or industry professional (including </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">BlackRock Fund Advisors (</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">BFA</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">) and its affiliates) (each, a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">Financial Intermediary</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">), which are not reflected in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;">the table and example below.</span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)1 0.0003 0 0.0003 0.0001 0.0002 0.0006 0.0006 June 30, 2027 Example: <div style="line-height: 10.695pt; margin-top: 0.0pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or lower, based on these assumptions your costs would be:</span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> 6 19 34 77 Portfolio Turnover: <div style="line-height: 10.695pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Master Portfolio pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Example, affect the Fund’s performance. During the most recent fiscal year, the Master Portfolio’s portfolio turnover </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">rate was </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">12</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">% of the average value of its portfolio.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> 0.12 Principal Investment Strategies of the Fund <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Large-Cap Index Fund employs a “passive” management approach, attempting to invest in a portfolio of assets </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">whose performance is expected to match approximately the performance of the Russell 1000. The Fund will be </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">substantially invested in equity securities in the Russell 1000, and will invest, under normal circumstances, at least </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">80% of its net assets in securities or other financial instruments that are components of or have economic </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">characteristics similar to the securities included in the Russell 1000. Equity securities in which the Fund invests </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">include common stock, preferred stock and securities or other instruments whose price is linked to the value of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">common stock.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund will invest in the common stocks represented in the Russell 1000 in roughly the same proportions as their </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">weightings in the Russell 1000. As of March 31, 2026, the companies in the Russell 1000 have a market </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">capitalization ranging from $134.5 billion to $4.32 trillion. The Fund may also engage in futures transactions. At times, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the Fund may not invest in all of the common stocks in the Russell 1000, or in the same weightings as in the Russell </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">1000. At those times, the Fund chooses investments so that the market capitalizations, industry weightings and other </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">fundamental characteristics of the stocks chosen are similar to the Russell 1000 as a whole. The Fund may lend </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities with a value up to 33</span><span style="color: #000000; font-family: arial; font-size: 6pt; position: relative; top: -2.66pt;"> 1</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">∕</span><span style="color: #000000; font-family: arial; font-size: 6pt;">3</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">% of its total assets to financial institutions that provide cash or securities issued or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">guaranteed by the U.S. Government as collateral. The Fund will concentrate its investments (i.e., hold 25% or more of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">its total assets) in a particular industry or group of industries to approximately the same extent that the Russell 1000 </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">is concentrated.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund is a “feeder” fund that invests all of its assets in the Master Portfolio, which has the same investment </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">objective and strategies as the Fund. All investments are made at the Master Portfolio level. This structure is </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investment results of the Master Portfolio. For simplicity, this prospectus uses the name of the Fund or the term </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“Fund” (as applicable) to include the Master Portfolio.</span></div> <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The Fund intends to be diversified in approximately the same proportion as the Underlying Index is diversified. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund may become </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">non-diversified,</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> as defined in the Investment Company Act of 1940, as amended, solely as a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">result of a change in relative market capitalization or index weighting of one or more constituents of the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index. Shareholder approval will not be sought if the Fund becomes </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">non-diversified</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> due solely to a change in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">relative market capitalization or index weighting of one or more constituents of the Underlying Index.</span></div> You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Concentration Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund reserves the right to concentrate its investments (i.e., invest 25% or more of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">total assets in securities of issuers in a particular industry) to approximately the same extent that the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index concentrates in a particular industry. To the extent the Fund concentrates in a particular industry, it may be </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">more susceptible to economic conditions and risks affecting that industry.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Equity Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Stock markets are volatile. The price of equity securities fluctuates based on changes in a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">company’s financial condition and overall market and economic conditions.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Information Technology Sector Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— IT companies face intense competition, both domestically and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">internationally, which may have an adverse effect on their profit margins. Like other technology companies, IT </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">companies may have limited product lines, markets, financial resources or personnel. The products of IT companies </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may face obsolescence due to rapid technological developments, frequent new product introduction, unpredictable </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div style="line-height: 10.695pt; margin-left: 12pt; text-align: left;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">changes in growth rates and competition for the services of qualified personnel. Companies in the IT sector are </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">heavily dependent on patent and intellectual property rights. The loss or impairment of these rights may adversely </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">affect the profitability of these companies. Companies in the IT sector may face increased government and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">regulatory scrutiny and may be subject to adverse government or regulatory action. Companies in the application </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">software industry, in particular, may also be negatively affected by the decline or fluctuation of subscription renewal </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">rates for their products and services, which may have an adverse effect on profit margins. Companies in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">systems software industry may be adversely affected by, among other things, actual or perceived security </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">vulnerabilities in their products and services, which may result in individual or class action lawsuits, state or federal </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">enforcement actions and other remediation costs.</span></div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Futures Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund’s use of futures may reduce the Fund’s returns. In these transactions, the Fund is </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">subject to liquidity risk and correlation risk (i.e., that fluctuations in a future’s value may not correlate with the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">change in market value of the instruments held by the Fund).</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Index-Related Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The Index Provider may rely on various sources of information to assess the criteria of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">components of the Underlying Index, including information that may be based on assumptions and estimates. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Neither the Fund nor BFA can offer assurances that the Index Provider’s methodology or sources of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">information will provide an accurate assessment of included components. Errors in index data, index computations </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or the construction of the Underlying Index in accordance with its methodology may occur, and the Index Provider </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may not identify or correct them promptly or at all, which may have an adverse impact on the Fund and its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">shareholders. Unusual market conditions or other unforeseen circumstances (such as natural disasters, political </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">unrest or war) may impact the Index Provider or a third-party data provider and could cause the Index Provider to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">postpone a scheduled rebalance. This could cause the Underlying Index to vary from its normal or expected </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">composition.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Large-Capitalization Companies Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Large-capitalization companies may be less able than smaller-capitalization </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">companies to adapt to changing market conditions and competitive challenges. Large-capitalization companies may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">be more mature and subject to more limited growth potential compared with smaller-capitalization companies. The </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance of large-capitalization companies could trail the overall performance of the broader securities markets. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund performance depends on the performance of individual securities to which the Fund has exposure. Changes in </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the financial condition or credit rating of an issuer of those securities may cause the value of the securities to </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">decline.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Market Risk and Selection Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— Market risk is the risk that one or more markets in which the Fund invests will </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">go down in value, including the possibility that the markets will go down sharply and unpredictably. The value of a </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">security or other asset may decline due to changes in general market conditions, economic trends or events that </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investments. Selection risk is the risk that the securities selected by Fund management will underperform the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">markets, the relevant indices or the securities selected by other funds with similar investment objectives and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">investment strategies. This means you may lose money.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Mid Cap Securities Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The securities of mid cap companies generally trade in lower volumes and are generally </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">subject to greater and less predictable price changes than the securities of larger capitalization companies.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Non</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">-Diversification Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-weight: bold;"> —</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> To the extent the Fund is non-diversified, the Fund may invest a large percentage of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">assets in securities or other instruments representing a small number of issuers or counterparties and thus may be </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">more susceptible to the risks associated with these particular issuers or counterparties. As a result, the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance may depend to a greater extent on the performance of a small number of issuers or counterparties, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">which may lead to more volatility in the Fund’s net asset value.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Operational and Technology Risks </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">— The Fund is directly and indirectly susceptible to operational and technology </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">risks, including those related to human errors, processing errors, communication errors, systems failures, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">cybersecurity incidents, and the use of artificial intelligence and machine learning (</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">“</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">AI</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">”</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">), which may result in losses </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">for the Fund and its shareholders or may impair the Fund’s operations. While the Fund’s service providers are </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">required to have appropriate operational, information security and cybersecurity risk management policies and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">procedures, their methods of risk management may differ from those of the Fund. Operational and technology risks </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">for the issuers in which the Fund invests could also result in material adverse consequences for such issuers and </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">may cause the Fund’s investments in such issuers to lose value.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Passive Investment Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> Because BFA does not select individual companies in the index that the Fund tracks, </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">the Fund may hold securities of companies that present risks that an investment adviser researching individual </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities might seek to avoid.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.0pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Preferred Securities Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — Preferred securities may pay fixed or adjustable rates of return. Preferred securities </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">preferred securities generally pay dividends only after the company makes required payments to holders of its </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">and other debt to actual or perceived changes in the company’s financial condition or prospects. Preferred </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities of smaller companies may be more vulnerable to adverse developments than preferred securities of </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">larger companies.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Securities Lending Risk</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> — The Fund may engage in securities lending. Securities lending involves the risk that the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">securities or a decline in the value of any investments made with cash collateral. These events could also trigger </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">adverse tax consequences for the Fund.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> <div> <div style="clear: both; margin-top: 4.805pt; position: relative; width: 100%;"> <div style="float: left; line-height: 9.87pt; text-align: left; width: 8pt;"><span style="color: #000000; font-family: arial; font-size: 8.37pt; position: relative; top: -0.5pt;">◼</span></div> <div style="float: left; line-height: 10.80pt; margin-left: 4pt; text-align: left; width: 505.00pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic; font-weight: bold;">Tracking Error Risk </span><span style="color: #000000; font-family: arial; font-size: 9.30pt; font-style: italic;">—</span><span style="color: #000000; font-family: arial; font-size: 9.30pt;"> The Fund is subject to the risk of “tracking error,” which is the divergence of the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">performance from that of the Underlying Index. Tracking error may occur due to a number of factors, including </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">differences between the securities and other assets held in the Fund’s portfolio and those included in the </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Underlying Index; differences in the timing and methodologies used to value securities and other assets; </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">transaction costs and other expenses incurred by the Fund that the Underlying Index does not incur; the Fund’s </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">holding of uninvested cash; differences in the timing of the accrual or the valuation of dividends or interest received </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">by the Fund or distributions paid to Fund shareholders; tax gains or losses; differences between the amount and/or </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">timing of withholding taxes on dividends reflected in the Underlying Index from the Fund’s obligation, if any, for </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">foreign withholding taxes; the requirements for the Fund to maintain pass-through tax treatment; portfolio </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">transactions carried out to minimize the distribution of capital gains to shareholders; changes to the Underlying </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">Index, such as during a rebalancing or reconstitution; and impacts to the Fund of complying with certain regulatory </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">requirements or limits. A fund that tracks an index composed of a large number of securities or other assets may </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">experience greater tracking error than a fund that tracks a more narrow index. Tracking error risk may be heightened </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">during times of increased market volatility or other unusual market conditions.</span></div> </div> <div style="clear: both; position: relative;"> </div> </div> Performance Information <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">The information shows you how the performance of Large-Cap Index Fund has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Russell 1000. To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. As with all such investments, past performance (before and after taxes) is not an indication of future results. The table includes all applicable fees. If BFA, BAL and their affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance, including its current net asset value, can be obtained by visiting www.blackrock.com or can be obtained by phone at (800) 882-0052.</span></div> The information shows you how the performance of Large-Cap Index Fund has varied year by year and provides some indication of the risks of investing in the Fund. As with all such investments, past performance (before and after taxes) is not an indication of future results. www.blackrock.com (800) 882-0052 Class K Shares ANNUAL TOTAL RETURNS iShares Russell 1000 Large-Cap Index Fund As of 12/31 <div style="margin-top: 6pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">During the ten-year period shown in the bar chart, the highest return for a quarter was 21.76% (quarter ended </span><span style="color: #000000; font-family: arial; font-size: 9.30pt;">June 30, 2020) and the lowest return for a quarter was -20.22% (quarter ended March 31, 2020).</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span><span style="color: #000000; font-family: arial; font-size: 1pt; line-height: 0.93pt;"> </span></div> highest return 0.2176 2020-06-30 lowest return -0.2022 2020-03-31 For the periods ended 12/31/25Average Annual Total Returns 0.1727 0.1354 0.1451 0.1637 0.1289 0.1374 0.1064 0.1063 0.1189 0.1737 0.1359 0.1459 <div style="margin-top: 12pt;"><span style="color: #000000; font-family: arial; font-size: 9.30pt;">After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.</span><span style="color: #000000; font-family: arial; font-size: 9.30pt; line-height: 10.695pt;"> </span></div> After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts. The fees and expenses shown in the table above and the example that follows include both the expenses of the Fund and its share of the allocated expenses of Total International ex U.S. Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio (“MIP”). The management fees are paid by the Master Portfolio. As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 45, BFA, the investment adviser for the Master Portfolio, has contractually agreed to waive the management fee with respect to any portion of the Master Portfolio’s assets estimated to be attributable to investments in other equity and fixed-income mutual funds and exchange-traded funds managed by BFA or its affiliates that have a contractual management fee, through June 30, 2027. In addition, BFA has contractually agreed to waive its management fees by the amount of investment advisory fees the Master Portfolio pays to BFA indirectly through its investment in money market funds managed by BFA or its affiliates, through June 30, 2027. The contractual agreements may be terminated upon 90 days’ notice by a majority of the non-interested trustees of MIP or by a vote of a majority of the outstanding voting securities of the Master Portfolio. Returns for net indices generally assume the reinvestment of dividends after the deduction of the maximum withholding tax in each country applicable to non-residents of the country as determined by the index provider. Such indices use withholding tax rates that are often at a higher rate than the rates to which the Fund is subject in each country, including for countries where the Fund is not subject to withholding taxes. When this is the case, index performance will be lower than if the index used the Fund’s applicable withholding tax rates, if any. The fees and expenses shown in the table above and the example that follows include both the expenses of the Fund and its share of the allocated expenses of Large Cap Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio (“MIP”). The management fees are paid by the Master Portfolio. As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 39, BFA, the investment adviser for the Master Portfolio, has contractually agreed to waive the management fee with respect to any portion of the Master Portfolio’s assets estimated to be attributable to investments in other equity and fixed-income mutual funds and exchange-traded funds managed by BFA or its affiliates that have a contractual management fee, through June 30, 2027. In addition, BFA has contractually agreed to waive its management fees by the amount of investment advisory fees the Master Portfolio pays to BFA indirectly through its investment in money market funds managed by BFA or its affiliates, through June 30, 2027. The contractual agreements may be terminated upon 90 days’ notice by a majority of the non-interested trustees of MIP or by a vote of a majority of the outstanding voting securities of the Master Portfolio. As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 39, BFA and BlackRock Advisors, LLC (“BAL”), the administrator for the Fund, have contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements of the Fund (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 0.08% of average daily net assets for Class K Shares through June 30, 2027. This contractual agreement may be terminated upon 90 days’ notice by a majority of the non-interested trustees of the Trust or of MIP, as applicable, or by a vote of a majority of the outstanding voting securities of the Fund or the Master Portfolio, as applicable. As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 45, BFA and BlackRock Advisors, LLC (“BAL”), the administrator for the Fund, have contractually agreed to waive and/or reimburse fees and/or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements of the Fund (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 0.41% (for Investor A Shares) and 0.16% (for Institutional Shares) of average daily net assets through June 30, 2027. This contractual agreement may be terminated upon 90 days’ notice by a majority of the non-interested trustees of the Trust or of MIP, as applicable, or by a vote of a majority of the outstanding voting securities of the Fund or the Master Portfolio, as applicable. Returns for net indices generally assume the reinvestment of dividends after the deduction of the maximum withholding tax in each country applicable to non-residents of the country as determined by the index provider. Such indices use withholding tax rates that are often at a higher rate than the rates to which the Fund is subject in each country, including for countries where the Fund is not subject to withholding taxes. When this is the case, index performance will be lower than if the index used the Fund’s applicable withholding tax rates, if any. As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 45, BFA, the investment adviser for the Master Portfolio, has contractually agreed to waive the management fee with respect to any portion of the Master Portfolio’s assets estimated to be attributable to investments in other equity and fixed-income mutual funds and exchange-traded funds managed by BFA or its affiliates that have a contractual management fee, through June 30, 2027. In addition, BFA has contractually agreed to waive its management fees by the amount of investment advisory fees the Master Portfolio pays to BFA indirectly through its investment in money market funds managed by BFA or its affiliates, through June 30, 2027. The contractual agreements may be terminated upon 90 days’ notice by a majority of the non-interested trustees of MIP or by a vote of a majority of the outstanding voting securities of the Master Portfolio. The fees and expenses shown in the table above and the example that follows include both the expenses of the Fund and its share of the allocated expenses of Large Cap Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio (“MIP”). The management fees are paid by the Master Portfolio. As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 45, BFA and BlackRock Advisors, LLC (“BAL”), the administrator for the Fund, have contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements of the Fund (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 0.38% (for Investor A Shares) and 0.13% (for Institutional Shares) of average daily net assets through June 30, 2027. This contractual agreement may be terminated upon 90 days’ notice by a majority of the non-interested trustees of the Trust or of MIP, as applicable, or by a vote of a majority of the outstanding voting securities of the Fund or the Master Portfolio, as applicable. The fees and expenses shown in the table above and the example that follows include both the expenses of the Fund and its share of the allocated expenses of Total International ex U.S. Index Master Portfolio (the “Master Portfolio”), a series of Master Investment Portfolio (“MIP”). The management fees are paid by the Master Portfolio. As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 39, BFA, the investment adviser for the Master Portfolio, has contractually agreed to waive the management fee with respect to any portion of the Master Portfolio’s assets estimated to be attributable to investments in other equity and fixed-income mutual funds and exchange-traded funds managed by BFA or its affiliates that have a contractual management fee, through June 30, 2027. In addition, BFA has contractually agreed to waive its management fees by the amount of investment advisory fees the Master Portfolio pays to BFA indirectly through its investment in money market funds managed by BFA or its affiliates, through June 30, 2027. The contractual agreements may be terminated upon 90 days’ notice by a majority of the non-interested trustees of MIP or by a vote of a majority of the outstanding voting securities of the Master Portfolio. As described in the “Management of the Funds” section of the Fund’s prospectus beginning on page 39, BFA and BlackRock Advisors, LLC (“BAL”), the administrator for the Fund, have contractually agreed to waive and/or reimburse fees and/or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements of the Fund (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 0.11% of average daily net assets for Class K Shares through June 30, 2027. This contractual agreement may be terminated upon 90 days’ notice by a majority of the non-interested trustees of the Trust or of MIP, as applicable, or by a vote of a majority of the outstanding voting securities of the Fund or the Master Portfolio, as applicable.