The Cheapest S&P 500 Index Funds

Check Out the Index Funds With Lowest Expense Ratios

While cheaper doesn't necessarily mean better, the best S&P 500 Index funds tend to be the ones with the lowest expense ratios. So before you go out and buy the cheapest index funds you can find, be sure to take a look at qualities of the fund other than the expenses.

Here are some of the qualities of index funds you'll want to analyze before thinking of buying.

Analyzing the Tracking Error and Performance to Find the Cheapest Index Funds

For example, there's something called tracking error, which is a measure of an index fund's effectiveness in replicating or "matching" the performance of the benchmark index.

One drawback with regard to researching and analyzing tracking error is that mutual fund families do not publicly display the tracking error of their index funds. However there are a few data points you can research to analyze performance tracking. You can start with our list of the cheapest S&P 500 Index funds here but you'll also want to compare performance.

You can go to one of the best websites for researching mutual funds and see how close the historical performance of the fund has been to the target benchmark. If the returns are below the benchmark by roughly the same amount as the fund's expense ratio (see below), the tracking error is close. For example, if a fund's expense ratio is 0.20% and it has a 5-year annualized return of 10.00%, and the benchmark had a return of 10.20%, the tracking error is precise. In summary you want the performance of your index funds to be below the benchmark by roughlyl an equal amount as the expense ratio. 

Analyzing the Expense Ratio to Find the Cheapest Index Funds

After looking at the historical performance, while taking the expense ratio into account, which will tell you how well the fund has tracked the benchmark index in the past. For example if an S&P 500 index mutual fund has an expense ratio of 0.20% and the S&P 500 index has a 5-year annualized return of 10.00%, an S&P 500 index fund with a good (low) tracking error might have an annualized return of roughly 9.80. This means that the only difference between the index and the mutual fund's return is attributed to the fund's expenses.

Before Buying the Cheapest Index Funds

Before looking at our list and buying your chosen S&P 500 Index fund, be sure to keep in mind other fees, such as trading costs. For example, if you already have an account at Vanguard, you may be charged a transaction fee to purchase a mutual fund, such as Schwab S&P 500 Index, which is outside of their fund family. Typical transaction fees range between $10 and $20.

So, if you are dollar-cost averaging by periodically purchasing shares of your S&P 500 Index fund, the expense ratio may be the lowest but the trading fees can make the fund more expensive than that of the fund company where you invest.

You will find some of the cheapest S&P 500 funds that you can buy with $10,000 or less listed below.

Fidelity Spartan S&P 500 Index Investor Class

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Fidelity Spartan 500 Index. Getty Images

Symbol:  FXAIX (Formerly FUSEX)

Net Expense Ratio: 0.015%

Minimum Initial Investment:  $0 (depending upon account type)

Schwab S&P 500 Index Fund

investing_index funds_screen
Schwab S&P 500 Index. Getty Images

Symbol:  SWPPX

Net Expense Ratio: 0.02%

Minimum Initial Investment:  $100

Vanguard 500 Index Fund Investor Shares

Vanguard S&P 500 Index. Getty Images

Symbol:  VFINX

Net Expense Ratio:  0.14%

Minimum Initial Investment:  $3,000

SSgA S&P 500 Index Fund

SSgA S&P 500 Index Fund. Getty Images

Symbol:  SVSPX

Net Expense Ratio:  0.16%

Minimum Initial Investment:  $10,000

T. Rowe Price Equity Index 500 Fund

investing_US dollar
T. Rowe Price Equity Index 500 Fund. Getty Images

Symbol:  PREIX

Net Expense Ratio: 0.21%

USAA S&P 500 Index Fund Member Shares

investing_coins_flower pots
USAA S&P 500 Index Member Shares. Getty Images

Symbol:  USSPX

Net Expense Ratio: 0.25%

Minimum Initial Investment:  $3,000