Prime Money Market Fund (VMMXX)

In accordance with the SEC's money market reform rules, institutional assets are no longer accepted into this fund. These assets include defined benefit, endowment and foundation, corporate, plan-sponsor directed defined contribution, and donor-advised fund assets. Instead, you may consider Vanguard Federal or Treasury money market funds, which are open to institutional assets.


Options Expense ratio Minimum
Investor 0.16% N/A
Admiral 0.10% $5.0 Million

About our options  



A fee charged by some mutual funds when an investor buys shares. This fee is not a sales charge or load because it is paid directly to the fund to offset the costs of trading certain securities.


A fee charged by some mutual funds when an investor sells shares. A redemption fee differs from a back-end load because the money is paid back into the fund. Many funds charge redemption fees only when shares are bought and then sold within a specific period of time, generally in an effort to discourage market-timing and short-term trading. Some brokers also charge their clients redemption fees for the sale of securities.



Product type: Taxable Money Market
Product type: Retail
 inception on 06/04/1975
$113.8 billion

This represents the total net assets for all share classes of Vanguard's U.S. funds, as well as any collective trust that shares the same investment strategy, management and holdings.

 as of 11/30/2018
$96.8 billion net assets for
 as of 11/30/2018
358 holdings as of 11/30/2018
Benchmarked to the Money Market Funds Average
Turnover rate (Fiscal year-end  08/31/2018) 0.00%

A non-money market fund's SEC yield is based on a formula mandated by the Securities and Exchange Commission (SEC) that calculates a fund's hypothetical annualized income, as a percentage of its assets. A security's income, for the purposes of this calculation, is based on the current market yield to maturity (in the case of bonds) or projected dividend yield (for stocks) of the fund's holdings over a trailing 30-day period. This hypothetical income will differ (at times, significantly) from the fund's actual experience; as a result, income distributions from the fund may be higher or lower than implied by the SEC yield.

The SEC yield for a money market fund is calculated by annualizing its daily income distributions for the previous seven days.



 7 day as of 12/07/2018
CUSIP: 922906201

Investment approach

  • Invests in high-quality money market instruments.
  • Seeks current income.
  • Seeks to maintain a constant $1 net asset value (NAV).
  • Maintains an average maturity of 60 days or less.

Total returns

as of 09/30/2018

View as:

as of 09/30/2018

  1 year 3 year 5 year 10 year


1.68% 0.97% 0.59% 0.43% 4.97%

Money Market Funds Average

1.24% 0.59% 0.35% 0.23%

Note: Fee adjusted for mutual funds where applicable.

* Derived from data provided by Lipper, a Thomson Reuters Company.

The performance data shown represent past performance, which is not a guarantee of future results. Investment returns and principal value will fluctuate, so investors' shares, when sold, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data cited.

People and process

Product management

Vanguard Prime Money Market Fund seeks to provide current income, while maintaining a stable $1 share price and a very short average maturity. The fund invests in a combination of high-quality commercial paper, certificates of deposit, bankers’ acceptances, and U.S. government securities. The portfolio managers seek to add value primarily by emphasizing specific issues and sectors that appear attractively priced based on historical yield-spread relationships. The average maturity typically ranges from 30–60 days, and the fund maintains a dollar-weighted average maturity of 60 days or less, and a dollar-weighted average life of 120 days or less.

Firm and manager details  


Money marketas of 11/30/2018 VMMXX

Money Market Funds Average

Number of holdings 358 N/A

Average effective maturity (taxable bond funds and balanced funds except Tax-Managed Balanced)
Average Effective Maturity is defined as the average length of time until fixed income securities held by a fund reach maturity and are repaid, taking into consideration that an action such as a call or refunding may cause some bonds to be repaid before they mature.

Average stated maturity (municipal bond funds and Tax-Managed Balanced)
Average stated maturity represents the average of the stated maturity dates for all fixed income securities held by the fund.

Average maturity (money market funds only)
Average maturity represents the weighted average maturity of the fund's holdings using the date of the next interest rate adjustment for certain adjustable-rate securities held by the fund.

46.0 (days) N/A
Weighted average life 103.0 (days) N/A

Risk and volatility

The fund is designed for investors with a low tolerance for risk; however, the fund’s performance could be hurt by:

  • Income risk: 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: The chance that poor security selection will cause the fund to underperform relevant benchmarks or other funds with a similar investment objective.
  • Credit risk: The chance that the issuer of a security will fail to pay interest or 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: The chance that there will be overall problems affecting a particular industry. Because the fund will invest more than 25% of its assets in securities of companies in the financial services industry, the fund’s performance will depend to a greater extent on the overall condition of that industry.

**The yield quotation more closely reflects the current earnings of the fund than the total return quotation.

The fund is only available to retail investors (natural persons). You could lose money by investing in the fund. Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so. The fund may impose a fee upon sale of your shares or may temporarily suspend your ability to sell shares if the fund’s liquidity falls below required minimums because of market conditions or other factors. An investment in the fund is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The fund’s sponsor has no legal obligation to provide financial support to the fund, and you should not expect that the sponsor will provide financial support to the fund at any time.