The Best S&P 500 Index Funds for Different Investors

Which S&P 500 index funds cost the least and track most accurately

The lowest-cost S&P 500 index funds are Vanguard VOO, iShares IVV, and SPDR SPY, each charging between 0.03% and 0.04% per year in expense ratios. All three track the index with near-identical accuracy because they hold the same 500 stocks in the same weights. The choice between them comes down to where you hold the account and what other funds you already own — not performance, which will be virtually identical over any meaningful time period.

If you are choosing between a brokerage account and a retirement account, the fund available in your retirement plan often matters more than which fund you pick. Many employers offer one S&P 500 fund through their 401(k), and using it means lower trading costs and automatic payroll deduction. If you are opening your own account at a brokerage, all three of these funds are available at every major broker with no transaction fees.

The difference between 0.03% and 0.04% per year is real but small — on a $10,000 investment, it amounts to $1 per year. Over decades, that difference compounds, but it should not be your only decision point. Ease of use, account type, and whether you already hold other funds at a particular brokerage often matter more in practice.

Key Takeaways

• Vanguard VOO, iShares IVV, and SPDR SPY all charge 0.03% to 0.04% annually and track the S&P 500 with nearly identical accuracy.
• The fund offered in your employer 401(k) plan is often the best choice because it avoids trading fees and integrates with payroll.
• All three major funds are available at every major brokerage with no purchase or sale fees.
• Expense ratio differences of 0.01% matter over decades but should not override convenience or account type.

S&P 500 index funds in employer retirement plans

Most large employers offer at least one S&P 500 index fund in their 401(k) plan, often under the Vanguard, Fidelity, or T. Rowe Price label. The specific fund name varies — you might see "Vanguard 500 Index Fund" or "Fidelity Spartan 500 Index Fund" — but the expense ratio is usually between 0.03% and 0.05%. Check your plan's investment menu to see what is available.

Using your employer's S&P 500 fund has two practical advantages. First, contributions come straight from your paycheck before taxes, so you do not have to remember to invest the money yourself. Second, you avoid trading fees that some brokerages charge when you buy or sell funds outside their own family. If your employer offers an S&P 500 index fund, it is almost always the simplest choice.

If your employer plan offers only actively managed funds or funds with expense ratios above 0.10%, you may want to maximize your 401(k) contribution to get any employer match, then open an individual IRA or brokerage account for additional investing. That way you get the match (assistance programs) but can choose lower-cost index funds for the rest.

S&P 500 index funds in IRAs and brokerage accounts

If you are opening an account on your own, Vanguard VOO, iShares IVV, and SPDR SPY are available at every major brokerage — Fidelity, Charles Schwab, E*TRADE, Merrill Edge, and others. All three charge 0.03% to 0.04% annually. You can buy or sell any of them with no transaction fee at any of these brokerages.

Vanguard VOO is the largest by assets under management, which means it has the tightest bid-ask spread (the difference between the price you pay to buy and the price you receive to sell). For most investors, this difference is negligible — a fraction of a cent per share — but it matters slightly more if you are trading frequently or with very large amounts.

If you already hold other Vanguard funds, VOO integrates seamlessly into a Vanguard account. The same is true for iShares funds at brokerages that prioritize iShares products, or SPDR funds at brokerages that emphasize SPDR. In practice, this rarely matters for a buy-and-hold investor, but it can simplify record-keeping and tax reporting if all your funds are from the same family.

Mutual funds versus ETFs: which structure to choose

S&P 500 index funds come in two structures: mutual funds and exchange-traded funds (ETFs). Vanguard offers both — the mutual fund version is called Vanguard 500 Index Fund (ticker VFIAX), and the ETF version is VOO. They hold the same stocks and charge the same 0.03% expense ratio, but they work differently.

A mutual fund is priced once per day after the market closes. You buy or sell at that day's closing price, no matter what time you place your order. An ETF trades throughout the day like a stock, so you can buy or sell at any time the market is open and see the price change in real time. For a long-term investor who buys once a month or once a quarter, this difference does not matter. For someone who trades frequently, ETFs offer more control over timing.

Mutual funds are simpler to set up automatic investments — many brokerages let you schedule monthly contributions directly into a mutual fund. ETFs require you to place a trade each time, which takes an extra step. If you plan to invest the same amount every month, a mutual fund may be more convenient. If you prefer to see live prices and have full control over when your order executes, an ETF is the better choice.

How to compare S&P 500 index funds you are considering

When you are looking at an S&P 500 index fund, check three things: the expense ratio (the annual cost as a percentage of your investment), the fund's assets under management (larger funds usually have tighter trading spreads), and whether it is available in the account type you want to use.

The expense ratio is listed in the fund's prospectus or fact sheet, which you can find on the fund company's website. For S&P 500 index funds, anything above 0.10% is expensive by current standards; anything between 0.03% and 0.05% is competitive. Do not pay attention to past performance — all S&P 500 index funds track the same index and will have nearly identical returns before fees.

If you are comparing funds across different brokerages, check whether you can buy the fund without a transaction fee. Most major brokerages waive fees for their own funds and for popular index funds from other families, but some smaller brokerages or older accounts may charge. A $10 transaction fee wipes out years of expense ratio savings on a small account.

When to choose a different type of index fund instead

An S&P 500 index fund holds only large U.S. companies. If you want exposure to mid-size or small U.S. companies, you would add a total U.S. stock market index fund (which includes the S&P 500 plus smaller companies) or a separate small-cap index fund. If you want international stocks, you would add a total international stock market index fund or a developed markets index fund.

Many investors build a portfolio with just two or three index funds: a total U.S. stock market fund, a total international stock market fund, and a bond index fund. An S&P 500 fund alone is a reasonable choice if you want simplicity and are comfortable with exposure only to large U.S. companies, but it is not a complete portfolio by itself.

If you are just starting out and want the simplest possible approach, a target-date fund (which automatically adjusts between stocks and bonds as you approach retirement) or a total stock market index fund may be easier than building your own mix. These are not better or worse than an S&P 500 fund — they are just different ways to organize the same underlying investments.

Frequently Asked Questions

Is VOO or IVV or SPY better for long-term investing?

For a buy-and-hold investor, the differences are too small to matter. All three charge 0.03% to 0.04% annually and track the index with near-identical accuracy. Choose based on which brokerage you use, which account type you prefer (mutual fund or ETF), or which fund your employer offers. Over 20 years, the difference in cost between them will be a few hundred dollars on a $100,000 investment — real money, but not enough to override convenience.

Can I switch between S&P 500 index funds without tax consequences?

In a 401(k) or IRA, you can switch between funds with no tax consequences. In a regular brokerage account, selling one fund to buy another triggers a taxable event if the fund has gained value. You will owe capital gains tax on the profit. If you are just starting out, pick a fund and stick with it rather than switching later.

What if my brokerage does not offer VOO or IVV?

Every major brokerage offers at least one of these three funds. If you are at a smaller or older brokerage, check whether they offer any S&P 500 index fund with an expense ratio below 0.10%. If they do not, opening an account at Fidelity, Charles Schwab, or Vanguard (all free to open) gives you access to the lowest-cost options.

Should I buy an S&P 500 fund or a total stock market fund?

A total stock market index fund includes the S&P 500 plus mid-cap and small-cap stocks. It is slightly more diversified but costs the same to own. If you are building a one-fund portfolio, a total stock market fund is marginally better. If you are combining an S&P 500 fund with other funds (like an international fund), the choice between them does not matter much.

Do I need to rebalance an S&P 500 index fund?

No. The fund itself rebalances automatically to stay aligned with the index. You do not need to do anything except hold it and add money over time. The fund company handles all the buying and selling needed to track the index.