April 28, 2026
Summary Prospectus
Vanguard Total Bond Market II Index Fund
Investor Shares
Vanguard Total Bond Market II Index Fund Investor Shares (VTBIX)
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 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
Vanguard Total Bond Market II Index Fund (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 Investor 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
Account Service Fee Per Year
(for certain fund account balances below $5,000,000)
$25
Annual Fund Operating Expenses
(Expenses that you pay each year as a percentage of the value of your investment) 
 
Management Fees
0.08
%
12b-1 Distribution Fee
None
Other Expenses
0.01
%
Total Annual Fund Operating Expenses
0.09
%
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
$9
$29
$51
$115
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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 107% of the average value of its portfolio.
Principal Investment Strategies
The Fund employs an indexing investment approach designed to track the performance of the Bloomberg U.S. Aggregate Float Adjusted Index (the “Target Index”). The Target Index measures the performance of 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. Under normal circumstances, the Fund invests at least 80% of its net assets, plus the amount of any borrowings for investment purposes, in the bonds that make up the Target Index and in securities that the advisor determines have substantially identical economic characteristics to the securities that make up the Target Index.   
The Fund invests by sampling the Target Index, meaning that it holds a range of securities that, in the aggregate, approximates the full Target Index in terms of key risk factors and other characteristics. The Fund maintains a dollar-weighted average maturity consistent with that of the Target Index. As of December 31, 2025, the dollar-weighted average maturity of the Target Index was 8.2 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.
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• 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.
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• 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.
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 Investor Shares has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Investor Shares compare with those of a broad-based securities market index. Keep in mind that the Fund’s past
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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 Total Bond Market II Index Fund Investor Shares
  
During the periods shown in the bar chart, the highest and lowest returns for a calendar quarter were: 
 
Total Return
Quarter
Highest
6.64
%
December 31, 2023
Lowest
-6.01
%
March 31, 2022
Average Annual Total Returns for Periods Ended December 31, 2025 
 
1 Year
5 Years
10 Years
Vanguard Total Bond Market II Index Fund
Investor Shares
Return Before Taxes
7.09
%
-0.47
%
1.90
%
Return After Taxes on Distributions
5.40
-1.67
0.73
Return After Taxes on Distributions and Sale of
Fund Shares
4.17
-0.87
0.96
Bloomberg U.S. Aggregate Float Adjusted Index
(reflects no deduction for fees, expenses, or taxes)
7.21
%
-0.37
%
2.05
%
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.
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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 Manager
Joshua C. Barrickman, CFA, Principal of Vanguard and Portfolio Manager at VCM. He has managed the Fund since 2010.
Purchase and Sale of Fund Shares
The Fund’s Investor Shares are generally available only to Vanguard funds that operate as funds of funds and to certain similar trusts and accounts. The Fund is currently not available for purchase by members of the public.
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.
“Bloomberg®” and 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 Total Bond Market II 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 Total Bond Market II Index Fund Investor Shares—Fund Number 635
To request additional information about the Fund, please visit vanguard.com or contact us at 800-662-7447.
© 2026 The Vanguard Group, Inc. All rights reserved.
Vanguard Marketing Corporation, Distributor.
SP 635 042026