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Institutional | Vanguard Long-Term Treasury Index Fund

Vanguard Long-Term Treasury Index Fund

Investment Objective

The Fund seeks to track the performance of a market-weighted Treasury index with a long-term dollar-weighted average maturity.

Fees and Expenses

The following table describes the fees and expenses you may pay if you buy and hold Institutional Shares of the Fund.

Shareholder Fees (Fees paid directly from your investment)

Shareholder Fees	Institutional Vanguard Long-Term Treasury Index Fund Institutional Shares
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)

Annual Fund Operating Expenses	Institutional Vanguard Long-Term Treasury Index Fund Institutional Shares
Management Fees	0.04%
12b-1 Distribution Fee	none
Other Expenses	0.01%
Total Annual Fund Operating Expenses	0.05%

Example

The following example is intended to help you compare the cost of investing in the Fund's Institutional Shares with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you were to invest $10,000 in the Fund's shares. This example assumes that the shares provide a return of 5% each year and that total annual fund operating expenses remain as stated in the preceding table. You would incur these hypothetical expenses whether or not you were to redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example	1 Year	3 Years	5 Years	10 Years
Institutional | Vanguard Long-Term Treasury Index Fund | Institutional Shares | USD ($)	5	16	28	64

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 more taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the previous expense example, reduce the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 16% 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 Barclays U.S. Long Treasury Bond Index. This Index includes fixed income securities issued by the U.S. Treasury (not including inflation- protected bonds), with maturities greater than 10 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 25.1 years.

Principal Risks

An investment in the Fund could lose money over short or long periods of time. You should expect the Fund's share price and total return to fluctuate within a wide range. The Fund is subject to the following risks, which could affect the Fund's performance:

• Interest rate risk, which is the chance that bond prices will decline because of rising interest rates. Interest rate risk should be high for the Fund because it invests primarily in long-term bonds, whose prices are more sensitive to interest rate changes than are the prices of shorter-term bonds.

• Income risk, which is the chance that the Fund's income will decline because of falling interest rates. Income risk should be low for the Fund because it invests primarily in long-term bonds.

• Index sampling risk, which is the chance that the securities selected for the Fund, in the aggregate, will not provide investment performance matching that of the Fund's target index. Index sampling risk for the Fund is expected to be low.

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 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. Long Treasury Index reflects the performance of the Bloomberg Barclays U.S. Long Government Float Adjusted Index through December 11, 2017, and the Bloomberg Barclays U.S. Long Treasury 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.

Annual Total Returns — Vanguard Long-Term Treasury Index Fund Institutional Shares

During the periods shown in the bar chart, the highest return for a calendar quarter was 24.37% (quarter ended September 30, 2011), and the lowest return for a quarter was –11.87% (quarter ended December 31, 2016).

Average Annual Total Returns for Periods Ended December 31, 2018

Average Annual Total Returns - Institutional - Vanguard Long-Term Treasury Index Fund		1 Year	5 Years	Since Inception	Inception Date
Institutional Shares		(1.63%)	5.99%	5.01%	Jul. 30, 2010
Institutional Shares | Return After Taxes on Distributions		(2.73%)	4.76%	3.77%	Jul. 30, 2010
Institutional Shares | Return After Taxes on Distributions and Sale of Fund Shares		(0.98%)	4.09%	3.37%	Jul. 30, 2010
Bloomberg Barclays U.S. Long Treasury Bond Index	[1]	(1.84%)	5.93%	5.04%	Jul. 30, 2010
Spliced Bloomberg Barclays U.S. Long Treasury Index	[1]	(1.84%)	5.90%	5.02%	Jul. 30, 2010

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.

[1] The year-to-date return as of the most recent calendar quarter, which ended on September 30, 2019, was 19.59%.

[1] Comparative Indexes (reflect no deduction for fees, expenses, or taxes)