VTWV Vangard Russell 2000 Value

Vanguard Short-Term Treasury Index Fund Summary Prospectus

December 20, 2019

Institutional Shares

Vanguard Short-Term Treasury Index Fund Institutional Shares (VSBIX)

The Fund's statutory Prospectus and Statement of Additional Information dated December 20, 2019, 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. You can also obtain this information at no cost by calling 800-662-7447 (if you are an individual investor) or 888-809-8102 (if you are a client of Vanguard's Institutional Division) or by sending an email request to online@vanguard.com.

See the inside front cover for important information about access to your fund's annual and semiannual shareholder reports.

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.

Important information about access to shareholder reports

Beginning on January 1, 2021, as permitted by regulations adopted by the SEC, paper copies of your fund's annual and semiannual shareholder reports will no longer be sent to you by mail, unless you specifically request them. Instead, you will be notified by mail each time a report is posted on the website and will be provided with a link to access the report.

If you have already elected to receive shareholder reports electronically, you will not be affected by this change and do not need to take any action. You may elect to receive shareholder reports and other communications from the fund electronically by contacting your financial intermediary (such as a broker-dealer or bank) or, if you invest directly with the fund, by calling Vanguard at one of the phone numbers on the back cover of this prospectus or by logging on to vanguard.com.

You may elect to receive paper copies of all future shareholder reports free of charge. If you invest through a financial intermediary, you can contact the intermediary to request that you continue to receive paper copies. If you invest directly with the fund, you can call Vanguard at one of the phone numbers on the back cover of this prospectus or log on to vanguard.com. Your election to receive paper copies will apply to all the funds you hold through an intermediary or directly with Vanguard.

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Principal Investment Strategies

The Fund employs an indexing investment approach designed to track the performance of the Bloomberg Barclays US Treasury 1–3 Year Bond Index. This Index includes fixed income securities issued by the U.S. Treasury (not including inflation-protected securities), all with maturities between 1 and 3 years.

The Fund invests by sampling the Index, meaning that it holds a range of securities that, in the aggregate, approximates the full Index in terms of key risk factors and other characteristics. All of the Fund's investments will be selected through the sampling process, and under normal circumstances, at least 80% of the Fund's assets will be invested in bonds included in the Index. The Fund maintains a dollar- weighted average maturity consistent with that of the Index. As of August 31, 2019, the dollar-weighted average maturity of the Index was 2 years.

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Annual Total Returns

The following bar chart and table 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 the Fund's target index and a comparative index, which have investment characteristics similar to those of the Fund. The Spliced Bloomberg Barclays U.S. Treasury 1-3 Year Index reflects the performance of the Bloomberg Barclays U.S. 1-3 Year Government Float Adjusted Index through December 11, 2017, and the Bloomberg Barclays US Treasury 1-3 Year Bond 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 or by calling Vanguard toll-free at 800-662-7447.

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Average Annual Total Returns for Periods Ended December 31, 2018

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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investors in the Short-Term Treasury Index Fund. The Index is licensed for use by The Vanguard Group, Inc. (Vanguard) as the sponsor of the Short-Term Treasury Index Fund. Bloomberg and Barclays' only relationship with Vanguard in respect to the Index is the licensing of the Index, which is determined, composed and calculated by BISL, or any successor thereto, without regard to the Issuer or the Short-Term Treasury Index Fund or the owners of the Short-Term Treasury Index Fund.

Additionally, Vanguard may for itself execute transaction(s) with Barclays in or relating to the Index in connection with the Short-Term Treasury Index Fund. Investors acquire the Short-Term Treasury Index Fund from Vanguard and investors neither acquire any interest in the Index nor enter into any relationship of any kind whatsoever with Bloomberg or Barclays upon making an investment in the Short-Term Treasury Index Fund. The Short-Term Treasury Index Fund is not sponsored, endorsed, sold or promoted by Bloomberg or Barclays. Neither Bloomberg nor Barclays makes any representation or warranty, express or implied regarding the advisability of investing in the Short-Term Treasury Index Fund or the advisability of investing in securities generally or the ability of the Index to track corresponding or relative market performance. Neither Bloomberg nor Barclays has passed on the legality or suitability of the Short-Term Treasury Index Fund with respect to any person or entity. Neither Bloomberg nor Barclays is responsible for and has not participated in the determination of the timing of, prices at, or quantities of the Short-Term Treasury Index Fund to be issued. Neither Bloomberg nor Barclays has any obligation to take the needs of the Issuer or the owners of the Short-Term Treasury Index Fund or any other third party into consideration in determining, composing or calculating the Index. Neither Bloomberg nor Barclays has any obligation or liability in connection with administration, marketing or trading of the Short-Term Treasury Index Fund.

The licensing agreement between Bloomberg and Barclays is solely for the benefit of Bloomberg and Barclays and not for the benefit of the owners of the Short-Term Treasury Index Fund, investors or other third parties. In addition, the licensing agreement between Vanguard and Bloomberg is solely for the benefit of Vanguard and Bloomberg and not for the benefit of the owners of the Short-Term Treasury Index Fund, investors or other third parties.

NEITHER BLOOMBERG NOR BARCLAYS SHALL HAVE ANY LIABILITY TO THE ISSUER, INVESTORS OR TO OTHER THIRD PARTIES FOR THE QUALITY, ACCURACY AND/OR COMPLETENESS OF THE BLOOMBERG BARCLAYS INDEX OR ANY DATA INCLUDED THEREIN OR FOR INTERRUPTIONS IN THE DELIVERY OF THE BLOOMBERG BARCLAYS INDEX. NEITHER BLOOMBERG NOR BARCLAYS MAKES ANY WARRANTY, EXPRESS OR IMPLIED, AS TO RESULTS TO BE OBTAINED BY THE ISSUER, THE INVESTORS OR ANY OTHER PERSON OR ENTITY FROM THE USE OF THE BLOOMBERG BARCLAYS INDEX OR ANY DATA INCLUDED THEREIN. NEITHER BLOOMBERG NOR BARCLAYS MAKES ANY EXPRESS OR IMPLIED WARRANTIES, AND EACH HEREBY EXPRESSLY DISCLAIMS ALL WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE OR USE WITH RESPECT TO THE BLOOMBERG BARCLAYS INDEX OR ANY DATA INCLUDED THEREIN. BLOOMBERG RESERVES THE RIGHT TO CHANGE THE METHODS OF CALCULATION OR PUBLICATION, OR TO CEASE THE CALCULATION OR PUBLICATION OF THE BLOOMBERG BARCLAYS INDEX, AND NEITHER BLOOMBERG NOR BARCLAYS SHALL BE LIABLE FOR ANY MISCALCULATION OF OR ANY INCORRECT, DELAYED OR INTERRUPTED PUBLICATION WITH RESPECT TO THE BLOOMBERG BARCLAYS INDEX. NEITHER BLOOMBERG NOR BARCLAYS SHALL BE LIABLE FOR ANY DAMAGES, INCLUDING, WITHOUT LIMITATION, ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY LOST PROFITS AND EVEN IF ADVISED OF THE POSSIBILITY OF SUCH, RESULTING FROM THE USE OF A BLOOMBERG BARCLAYS INDEX OR ANY DATA INCLUDED THEREIN OR WITH RESPECT TO THE SHORT-TERM TREASURY INDEX FUND.

None of the information supplied by Bloomberg or Barclays and used in this publication may be reproduced in any manner without the prior written permission of both Bloomberg and Barclays Capital, the investment banking division of Barclays Bank Plc. Barclays Bank Plc is registered in England No. 1026167. Registered office 1 Churchill Place London E14 5HP.

To request additional information about the Fund, please visit vanguard.com or contact 800-662-7447 (if you are an individual investor) or 888-809-8102 (if you are a client of Vanguard's Institutional Division).

© 2019 The Vanguard Group, Inc. All rights reserved. Vanguard Marketing Corporation, Distributor.

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