There's safety in numbers, the old saying goes, and when it comes to mutual fund investing, it's not a bad principle. Larger funds typically have lower expense ratios, which may improve performance over time, and larger funds provide access to premiere money managers who specialize to a very granular level. (See also: Mutual Funds: The Costs.)

Currently, two companies dominate the domestic mutual fund market. Vanguard, with $4.5 trillion in assets under management (AUM) in its mutual funds, is the clear leader, with eight of the top ten largest mutual funds. Fidelity, with $1.97 trillion in AUM, is a distant second, but it is still more than respectable in terms of its family of funds. (See also: Fidelity vs. Vanguard: Which Is Better Suited to You?)

If you're looking to cash in on the potential advantages of size in your mutual fund investments, here are the five largest mutual funds for 2017. Note: All figures were current as of January 2018.

Vanguard Total Stock Market Index Fund Admiral (VTSAX)

Issuer: Vanguard

Assets under management: $657 billion

Expense ratio: 0.04 percent

1-year performance: 20.63 percent

3-year annualized performance: 10.54 percent

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Vanguard Total Stock Market Index Fund Investor Shares (VTSMX)

Issuer: Vanguard

Assets under management: $657 billion

Expense ratio: 0.15 percent

1-year performance: 20.51 percent

3-year annualized performance: 10.43 percent

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Vanguard 500 Index Fund Admiral Shares (VFIAX)

Issuer: Vanguard

Assets under management: $383 billion

Expense ratio: 0.04 percent

1-year performance: 21.23 percent

3-year annualized performance: 10.82 percent

Vanguard Institutional Index Mutual Fund (VINIX)

Issuer: Vanguard

Assets under management: $233 billion

Expense ratio: 0.04 percent

1-year performance: 21.23 percent

3-year annualized performance: 10.82 percent

 

Fidelity Government Cash Reserves (FDRXX)

Issuer: Fidelity

Assets under management: $135 billion

Expense ratio: 0.35 percent

1-year performance: 0.56 percent

3-year annualized performance: 0.22 percent

This is a very old, established money market fund that aims to preserve capital and liquidity for income investors. The fund's assets are virtually entirely invested in cash, CDs and government Treasury bills. If you're looking for a stable place to park some cash, this is a solid choice, with low expenses for a fund of this type. (See also: Introduction to Money Market Funds.)