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During the periods shown in the bar chart, the highest return for a calendar quarter was 1.34% (quarter ended December 31, 2006 ), and the lowest return for a quarter was 0.01% (quarter ended December 31, 2013 ).

During the periods shown in the bar chart, the highest return for a calendar quarter was 1.28% (quarter ended December 31, 2006 ), and the lowest return for a quarter was 0.00% (quarter ended March 31, 2013 ).

During the periods shown in the bar chart, the highest return for a calendar quarter was 1.29% (quarter ended December 31, 2006 ), and the lowest return for a quarter was 0.00% (quarter ended March 31, 2013 ).

During the periods shown in the bar chart, the highest return for a calendar quarter was 1.28% (quarter ended December 31, 2006 ), and the lowest return for a quarter was 0.00% (quarter ended March 31, 2013 ).

During the periods shown in the bar chart, the highest return for a calendar quarter was 1.29% (quarter ended December 31, 2006 ), and the lowest return for a quarter was 0.00% (quarter ended March 31, 2013 ).

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Annual Total Returns - Vanguard Prime Money Market Fund Institutional Shares

Annual Total Returns - Vanguard Federal Money Market Fund Investor Shares

Annual Total Returns - Vanguard Prime Money Market Fund Investor Shares

Annual Total Returns - Vanguard Federal Money Market Fund Investor Shares

Annual Total Returns - Vanguard Prime Money Market Fund Investor Shares

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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 invested $10,000 in the Fund's shares. This example assumes that the Shares provide a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you 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:

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $10,000 in the Fund's shares. This example assumes that the Fund provides a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you 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:

The following example is intended to help you compare the cost of investing in the Fund's Investor Shares with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $10,000 in the Fund's shares. This example assumes that the Shares provide a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you 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:

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $10,000 in the Fund's shares. This example assumes that the Fund provides a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you 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:

The following example is intended to help you compare the cost of investing in the Fund's Investor Shares with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $10,000 in the Fund's shares. This example assumes that the Shares provide a return of 5% a year and that total annual fund operating expenses remain as stated in the preceding table. The results apply whether or not you 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:

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Fees and Expenses

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(quarter ended December 31, 2006 )

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(quarter ended December 31, 2013 )

(quarter ended March 31, 2013 )

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The Fund seeks to provide current income while maintaining liquidity and a stable share price of $1.

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, which have investment characteristics similar to those of the Fund.

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vanguard.com/performance

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Keep in mind that the Fund's past performance does not indicate how the Fund will perform in the future.

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The Fund is subject to the risks associated with the stock and bond markets, any of which could cause an investor to lose money.

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The Fund is designed for investors with a low tolerance for risk; however, the Fund is subject to the following risks, which could affect the Fund's performance:

Income risk, which is the chance that the Fund's income will decline because of falling interest rates. Because the Fund's income is based on short-term interest rates-which can fluctuate significantly over short periods-income risk is expected to be high.

Manager risk, which is the chance that poor security selection will cause the Fund to underperform relevant benchmarks or other funds with a similar investment objective.

Credit risk, which is the chance that the issuer of a security will fail to pay interest and principal in a timely manner or that negative perceptions of the issuer's ability to make such payments will cause the price of that security to decline. Credit risk should be very low for the Fund because it invests primarily in securities that are considered to be of high quality.

Industry concentration risk, which is the chance that there will be overall problems affecting a particular industry. Because the Fund invests more than 25% of its assets in securities issued by companies in the financial services industry, the Fund's performance depends to a greater extent on the overall condition of that industry and is more susceptible to events affecting that industry.

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. Although the Fund seeks to preserve the value of your investment at $1 per share, it is possible to lose money by investing in the Fund.