SPI 869 Balanced Index Fund

April 28, 2026

Summary Prospectus

Vanguard Balanced Index Fund

Institutional Shares

Vanguard Balanced Index Fund Institutional Shares (VBAIX)

The Fund’s statutory Prospectus and Statement of Additional Information dated April 28, 2026, as may be amended or supplemented, are incorporated into and made part of this Summary Prospectus by reference.

Before you invest, you may want to review the Fund’s Prospectus, which contains more information about the Fund and its risks. You can find the Fund’s Prospectus and other information about the Fund online at www.vanguard.com/prospectus and https://personal.vanguard.com/us/literature/reports/MFs. You can also obtain this information at no cost by calling 800-662-7447 (if you are an individual investor) or 800-523-1036 (if you are a client of Vanguard’s Institutional Division) or by sending an email request to online@vanguard.com.

The Securities and Exchange Commission (SEC) has not approved or disapproved these securities or passed upon the adequacy of this Prospectus. Any representation to the contrary is a criminal offense.

Investment Objective

With 60% of its assets, Vanguard Balanced Index Fund (the “Fund”) seeks to track the performance of a benchmark index that measures the investment return of the overall U.S. stock market. With 40% of its assets, the Fund seeks to track the performance of a broad, market-weighted bond index.

Fees and Expenses

The following tables describe the fees and expenses you may pay if you buy, hold, and sell Institutional Shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and example below.

Shareholder Fees
(Fees paid directly from your investment)


Sales Charge (Load) Imposed on Purchases	None
Purchase Fee	None
Sales Charge (Load) Imposed on Reinvested Dividends	None
Redemption Fee	None

Annual Fund Operating Expenses
(Expenses that you pay each year as a percentage of the value of your investment)


Management Fees	0.04 %
12b-1 Distribution Fee	None
Other Expenses	0.00 %
Total Annual Fund Operating Expenses1	0.04 %

The expense information shown in the table has been restated to reflect current fees.

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same.

1 Year	3 Years	5 Years	10 Years
$4	$13	$23	$51

Portfolio Turnover

The Fund 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 Fund 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 Fund’s portfolio turnover rate was 31% of the average value of its portfolio.

Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of two benchmark indexes, the CRSP US Total Market Index (the “Equity Target Index”) and the Bloomberg U.S. Aggregate Float Adjusted Index (the “Bond Target Index”, and together with the Equity Target Index, the “Target Indexes”). The Fund invests by sampling the Target Indexes, meaning that it holds a range of securities that, in the aggregate, approximates the full Target Indexes in terms of key risk factors and other characteristics. Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in the securities that make up the Target Indexes and in securities that the advisor determines have substantially identical economic characteristics to the securities that make up the Target Indexes.

With approximately 60% of its assets, the Fund seeks to track the investment performance of the Equity Target Index, which represents approximately 100% of the investable U.S. stock market and includes large-, mid-, small-, and micro-cap stocks.

With approximately 40% of its assets, the Fund seeks to track the investment performance of the Bond Target Index, which represents a wide spectrum of public, investment-grade, taxable, bonds in the United States—including government, corporate, and international dollar-denominated bonds, as well as mortgage-backed and asset-backed securities—all with maturities of more than 1 year. The bond portion of the Fund seeks to maintain a dollar-weighted average maturity consistent with that of the Bond Target Index. As of December 31, 2025, the dollar-weighted average maturity of the Bond Target Index was 8.1 years.

Principal Risks

As with any investment, an investment in the Fund could lose money over any time period. The Fund’s share price and total return may fluctuate, potentially within a wide range. The principal risks of investing in the Fund are summarized below. Each of the following risks could affect the Fund’s performance:

• General Market Risk. The markets in which the Fund invests can be affected by a variety of factors. These factors, which can be real or perceived, may include economic, market, political, and regulatory conditions and developments as well as local, regional, or global events such as wars, military conflicts, natural disasters, and public health issues. In addition, investor sentiment and expectations regarding these factors can also impact the markets. Different parts of the market, including different industries and sectors as well as different types of securities, may react differently to factors that affect the market. These factors can contribute to market uncertainty, market volatility, and fluctuations in the value of the Fund’s investments, thereby resulting in potential losses to the Fund over short or long periods.

• Investing in Equity Markets. The Fund invests in the equity markets. Equity markets have historically been cyclical, having periods of time when stock

values rise and fall. Market volatility can lead to significant fluctuations in stock values, resulting in potential losses to the Fund.

• Market Capitalization (Market Cap). Companies are generally classified into three types of market cap depending on their size: small-, mid-, and large-cap. Companies can be further classified into micro- or mega-cap. Different factors can affect each market cap uniquely, and historically small- and mid-cap stocks have typically been more volatile due to the effects of changing economic conditions. Large companies may not reach the same levels of growth or performance as smaller companies, and they may be slower to react to competitive challenges. The performance of funds that invest in a subset of market caps could diverge from the performance of a fund that is focused on a broader representation of the stock market.

• Investing in Bond Markets. The Fund may be impacted by the general condition of the bond markets and by factors that affect bonds and bond issuers. For example, as a general rule, bond prices and interest rates move in opposite directions. When interest rates rise, bond prices tend to fall, and when interest rates fall, bond prices tend to go up. Bond income also is affected by changes in interest rates. Interest rates can rise or fall for a number of reasons, including, but not limited to, central bank monetary policy, inflationary or deflationary pressures, and changes in general market and economic conditions. Changing interest rates, including, but not limited to, rates that fall below zero, could have unpredictable effects on the overall market and may expose the bond markets in particular to heightened volatility and potential illiquidity. The degree to which the Fund is impacted by certain bond market risks may vary based on factors disclosed in its principal investment strategies, such as the types of bonds in which it invests and the overall credit quality, average maturity, and/or average duration of its bond holdings.

• Interest Rate Risk. During periods of rising interest rates, bond prices overall may decline, which could result in a decline in the Fund’s value. The prices of longer-term bonds are more sensitive to changes in interest rates than the prices of shorter-term bonds.

• Income Risk. During periods of falling interest rates, the Fund’s income may decline. The income paid by shorter-term bonds is subject to a higher degree of fluctuation than the income paid by longer-term bonds.

• Credit Risk. Credit risk refers to the chance that an issuer will default (fail to meet its credit obligations) or fail to make payments in a timely manner, which could result in a loss to the Fund. In addition, negative perceptions of an issuer’s ability to make payments can cause the price of a security to decline. While all debt securities are subject to credit risk to some extent, those with higher credit quality ratings generally pose less credit risk than those with lower credit quality ratings.

• Bond Liquidity Risk. If the Fund is unable to sell a security at an advantageous time or price, its returns may be reduced. There may be limited trading in the secondary market for certain debt securities, which could make them more difficult to value or sell.

• Call Risk. Certain bonds held by the Fund may be callable. The issuer of a callable bond has the right to “call” (redeem) the bond before its maturity date. Calls on bonds held by the Fund would result in the Fund losing any price appreciation above the bond’s call price. In addition, because bond calls occur more frequently during periods of falling interest rates, the Fund likely

would be forced to reinvest the proceeds of any called bonds at a lower interest rate than that of the called bonds, resulting in a decline in the Fund’s income and a potential loss in the value of the Fund’s investments. Frequent bond calls and subsequent reinvestments of the proceeds also would increase the Fund’s turnover rate.

• Prepayment Risk. Certain bonds are subject to risks associated with prepayment. Prepayment risk for callable bonds is described under Call Risk. With respect to mortgage-backed, asset-backed, and similar debt securities, prepayment typically refers to borrowers repaying their debt early (e.g., before the maturity date). Prepayment of bonds held by the Fund would result in the Fund losing any price appreciation above the amount repaid (or the bond’s call price, in the case of callable bonds). In addition, because prepayments occur more frequently in low interest rate environments, the Fund likely would be forced to reinvest the proceeds from any prepayments at a lower interest rate than when the prepaid bonds were purchased, resulting in a decline in the Fund’s income and a potential loss in the value of the Fund’s investments. Frequent prepayments and subsequent reinvestment of the proceeds also would increase the Fund’s turnover rate.

• Extension Risk. During periods of rising interest rates, certain bonds held by the Fund may be paid off substantially more slowly than originally anticipated. As a result, the value of the bonds may fall, resulting in a decline in the Fund’s income and a potential loss in the value of the Fund’s investments.

• Index Investing. The Fund is subject to risks associated with index investing. Because the Fund generally seeks to track the performance of the Target Index regardless of how the Target Index is performing, the Fund’s performance may be lower than it would be if it were actively managed. Additionally, because the Fund does not hold all of the securities included in the Target Index, it is subject to the risk that the representative sample of securities selected by the advisor will, in the aggregate, vary from the investment profile of the full Target Index. The performance of the Fund’s investments, in the aggregate, may not match the investment performance of the Target Index. This risk, known as tracking error risk, may be heightened during times of increased market volatility or under other unusual market conditions. The Fund also could be negatively impacted by changes to the Target Index made by the index provider or by errors made by the index provider. Any gains, losses, or costs associated with or resulting from an error made by the index provider will generally be borne by the Fund and, as a result, the Fund’s shareholders.

• Information Technology Sector. As of the Fund’s most recent fiscal year end, stocks of companies within the information technology sector made up a significant portion of the Target Index. As a result, the performance of the Target Index, and therefore the performance of the Fund, may be impacted by the general condition of the information technology sector.

An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Annual Total Returns

The following bar chart and table show the Fund’s historical performance and are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund’s Institutional Shares has varied

from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Institutional Shares compare with those of a broad-based securities market index and one or more additional indexes with similar investment characteristics as the Fund. The Balanced Composite Index is weighted 60% MSCI US Broad Market Index and 40% Bloomberg U.S. Aggregate Float Adjusted Index through January 14, 2013, and 60% CRSP US Total Market Index and 40% Bloomberg U.S. Aggregate Float Adjusted Index thereafter. Keep in mind that the Fund’s past performance (before and after taxes) does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance.

Annual Total Returns — Vanguard Balanced Index Fund Institutional Shares

During the periods shown in the bar chart, the highest and lowest returns for a calendar quarter were:

	Total Return	Quarter
Highest	14.24 %	June 30, 2020
Lowest	-12.13 %	June 30, 2022

Average Annual Total Returns for Periods Ended December 31, 2025

	1 Year	5 Years	10 Years
Vanguard Balanced Index Fund Institutional Shares
Return Before Taxes	13.59 %	7.76 %	9.51 %
Return After Taxes on Distributions	11.64	6.44	8.42
Return After Taxes on Distributions and Sale of Fund Shares	8.79	5.73	7.40
CRSP US Total Market Index (reflects no deduction for fees, expenses, or taxes)	17.15 %	13.08 %	14.25 %
Bloomberg U.S. Aggregate Float Adjusted Index (reflects no deduction for fees, expenses, or taxes)	7.21	-0.37	2.05
Balanced Composite Index (reflects no deduction for fees, expenses, or taxes)	13.57	7.89	9.69

Actual after-tax returns depend on your tax situation and may differ from those shown in the preceding table. When after-tax returns are calculated, it is assumed that the shareholder was in the highest individual federal marginal income tax bracket at the time of each distribution of income or capital gains or upon redemption. State and local income taxes are not reflected in the calculations. Please note that after-tax returns are not relevant for a

shareholder who holds fund shares in a tax-deferred account, such as an individual retirement account or a 401(k) plan. Also, figures captioned Return After Taxes on Distributions and Sale of Fund Shares may be higher than other figures for the same period if a capital loss occurs upon redemption and results in an assumed tax deduction for the shareholder.

Investment Advisor

The Vanguard Group, Inc. (Vanguard) through its wholly owned subsidiary, Vanguard Capital Management (VCM). VCM exercises portfolio management responsibilities for the Fund.

Portfolio Managers

Joshua C. Barrickman, CFA, Principal of Vanguard and Portfolio Manager at VCM. He has managed the bond portion of the Fund since 2013 (co-managed since 2022).

Aurélie Denis, CFA, Portfolio Manager at VCM. She has co-managed the stock portion of the Fund since 2023.

Michael R. Roach, CFA, Portfolio Manager at VCM. He has co-managed the stock portion of the Fund since 2023.

Tara Talone, CFA, Portfolio Manager at VCM. She has co-managed the bond portion of the Fund since 2022.

Purchase and Sale of Fund Shares

If you invest directly with Vanguard, you may purchase or redeem shares online through our website (vanguard.com), by mail (The Vanguard Group, P.O. Box 982901, El Paso, TX 79998-2901), or by telephone (800-662-2739). The minimum investment amount required to open a Fund account for Institutional Shares is generally $5 million. The minimum investment amount required to add to an existing Fund account is generally $1.

If you are investing through an employer-sponsored retirement or savings plan, your plan administrator or your benefits office can provide you with detailed information on how you can invest through your plan.

Tax Information

The Fund’s distributions may be taxable as ordinary income or capital gains. If you are investing through a tax-advantaged account, such as an IRA or an employer-sponsored retirement or savings plan, special tax rules apply. You should consult your own tax advisor with respect to any particular U.S. or non-U.S. tax consequences of your investment in the Fund.

Payments to Financial Intermediaries

The Fund and its advisor do not pay financial intermediaries for sales of Fund shares.

CFA® is a registered trademark owned by CFA Institute.

Center for Research in Security Prices, LLC (CRSP®) and its third-party suppliers have exclusive proprietary rights in the CRSP® Index Data, which has been licensed for use by Vanguard but is and shall remain valuable intellectual property owned by, and/or licensed to, CRSP®. The Vanguard Funds are not sponsored, endorsed, sold or promoted by CRSP®, The University of Chicago, or The University of Chicago Booth School of Business and neither CRSP®, The University of Chicago, or The University of Chicago Booth School of Business, make any representation regarding the advisability of investing in the Vanguard Funds.

“Bloomberg®” and the Bloomberg U.S. Aggregate Float Adjusted Index (the “Index”) are service marks of Bloomberg Finance L.P. and its affiliates, including Bloomberg Index Services Limited (“BISL”), the administrator of the index (collectively, “Bloomberg”), and have been licensed for use for certain purposes by Vanguard.

Vanguard Balanced Index Fund (the “Fund”) is not sponsored, endorsed, sold or promoted by Bloomberg. Bloomberg does not make any representation or warranty, express or implied, to the owners of or counterparties to the Fund or any member of the public regarding the advisability of investing in securities or commodities generally or in the Fund particularly. The only relationship of Bloomberg to Vanguard is the licensing of certain trademarks, trade names and service marks and of the Index, which are determined, composed and calculated by BISL without regard to Vanguard or the Fund. Bloomberg has no obligation to take the needs of Vanguard or the owners of the Fund into consideration in determining, composing or calculating the Index. Bloomberg is not responsible for and has not participated in the determination of the timing, price, or quantities of the Fund to be issued. Bloomberg shall not have any obligation or liability, including, without limitation, to customers of the Fund, in connection with the administration, marketing or trading of the Fund.

BLOOMBERG DOES NOT GUARANTEE THE ACCURACY AND/OR THE COMPLETENESS OF THE INDEX OR ANY DATA RELATED THERETO AND SHALL HAVE NO LIABILITY FOR ANY ERRORS, OMISSIONS OR INTERRUPTIONS THEREIN. BLOOMBERG DOES NOT MAKE ANY WARRANTY, EXPRESS OR IMPLIED, AS TO RESULTS TO BE OBTAINED BY VANGUARD, OWNERS OF THE FUND OR ANY OTHER PERSON OR ENTITY FROM THE USE OF THE INDEX OR ANY DATA RELATED THERETO. BLOOMBERG DOES NOT MAKE ANY EXPRESS OR IMPLIED WARRANTIES AND EXPRESSLY DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE WITH RESPECT TO THE INDEX OR ANY DATA RELATED THERETO. WITHOUT LIMITING ANY OF THE FOREGOING, TO THE MAXIMUM EXTENT ALLOWED BY LAW, BLOOMBERG, ITS LICENSORS, AND ITS AND THEIR RESPECTIVE EMPLOYEES, CONTRACTORS, AGENTS, SUPPLIERS, AND VENDORS SHALL HAVE NO LIABILITY OR RESPONSIBILITY WHATSOEVER FOR ANY INJURY OR DAMAGES—WHETHER DIRECT, INDIRECT, CONSEQUENTIAL, INCIDENTAL, PUNITIVE OR OTHERWISE—ARISING IN CONNECTION WITH THE FUND OR INDEX OR ANY DATA OR VALUES RELATING THERETO—WHETHER ARISING FROM THEIR NEGLIGENCE OR OTHERWISE, EVEN IF NOTIFIED OF THE POSSIBILITY THEREOF.

Vanguard Balanced Index Fund Institutional Shares—Fund Number 869

To request additional information about the Fund, please visit vanguard.com or contact us at 800-662-7447 (if you are an individual investor) or 800-523-1036 (if you are a client of Vanguard’s Institutional Division)

Vanguard Marketing Corporation, Distributor.

SPI 869 042026