What the S&P 500 is and why people invest in it

The S&P 500 is a list of 500 large U.S. companies chosen and maintained by Standard & Poor's, a financial data company. When people say they're investing in "the S&P 500," they mean buying a fund that holds all 500 of those stocks at once, rather than picking individual companies. The appeal is simple: you own a piece of 500 businesses with one purchase, so if one company stumbles, the others cushion the loss.

Most S&P 500 funds are index funds or exchange-traded funds (ETFs) — both track the same 500 companies and charge low fees because they don't require a manager to pick winners and losers. The difference is mainly how you buy them: index funds trade once per day at a set price, while ETFs trade throughout the day like individual stocks. For a homeowner saving for retirement or other long-term goals, either works.

Historically, the S&P 500 has returned roughly 10% per year on average over decades, though individual years vary widely — some years it gains 20%, others it loses 10% or more. That long history of growth is why it's a common choice for retirement accounts and taxable investment accounts.

Key Takeaways

  • You buy S&P 500 funds through a brokerage account — either a retirement account like a 401(k) or IRA, or a regular taxable account — not directly from the stock exchange.
  • The two main types are index funds and ETFs; both track the same 500 companies and charge similar low fees, so the choice depends on how you prefer to trade.
  • You need to open an account with a brokerage firm (Vanguard, Fidelity, Charles Schwab, and others), deposit money, and select the specific S&P 500 fund you want to buy.
  • Costs matter: look for funds with expense ratios under 0.10% per year, since even small fee differences compound over decades.
  • The S&P 500 is not a may provide investment; its value fluctuates daily, and past returns do not predict future results.

Opening a brokerage account

Before you can buy any S&P 500 fund, you need an account at a brokerage — a firm licensed to buy and sell investments on your behalf. Common brokerages include Vanguard, Fidelity, Charles Schwab, E*TRADE, and Merrill Edge. Most have no account minimums anymore, though some funds within them do (often $1,000 to $3,000 to start).

The account type matters. If you're saving for retirement, a 401(k) (through your employer) or an IRA (which you open yourself) offers tax advantages — you don't pay taxes on gains until you withdraw the money, or in some cases never. If you're saving for something else — a home repair fund, a vacation, or just extra money — you open a regular taxable brokerage account, where you pay taxes on gains each year but can withdraw anytime without penalty.

Opening an account takes 10 to 15 minutes online. You'll provide your name, address, Social Security number, employment information, and bank details. The brokerage verifies your identity and then you can fund the account by linking a bank account or transferring money.

Choosing which S&P 500 fund to buy

Once your account is open and funded, you search for S&P 500 funds by name or ticker symbol. The most common ones are VFIAX (Vanguard), FSKAX (Fidelity), and SPLG (SPDR), but dozens exist. All track the same 500 companies, so the main difference is the expense ratio — the annual fee charged as a percentage of your money.

A fund charging 0.03% per year costs $3 per $10,000 invested. One charging 0.20% costs $20 per $10,000. Over 30 years, that small difference compounds significantly. Look for funds with expense ratios under 0.10%; anything under 0.05% is excellent. The brokerage website shows the expense ratio clearly in the fund's details.

If you're buying through a 401(k) at work, your employer has already chosen which S&P 500 fund (or funds) to offer. You don't pick the brokerage — you pick from the menu your employer provides. If the options look expensive (expense ratios above 0.20%), ask your HR department why; sometimes they negotiate better rates than public websites show.

Making your first purchase

Once you've chosen a fund, buying it is straightforward. Log into your brokerage account, search for the fund by name or ticker, and place an order. You'll specify how much money to invest — either a dollar amount or a number of shares. Most people invest a lump sum once, but you can also set up automatic monthly transfers from your bank account, which many investors find easier than remembering to buy manually.

For index funds, your order processes once per day after the market closes, at that day's closing price. For ETFs, your order executes immediately during market hours at the current price, similar to buying a stock. Either way, the fund appears in your account within a few days, and you own your slice of all 500 companies.

After you buy, you don't have to do anything. The fund automatically rebalances itself to stay aligned with the S&P 500 as companies rise and fall. You simply hold it and let it grow. Many investors add money regularly — monthly or annually — rather than making one large purchase.

Understanding costs and taxes

Beyond the expense ratio, there are other costs to know about. Some brokerages charge a commission (a flat fee per trade), though most major ones have eliminated commissions for stock and fund purchases. Always check the brokerage's fee schedule before opening an account.

In a taxable account, you'll owe taxes on any gains when you sell the fund or when it distributes dividends (payments from the companies in the fund). Index funds and ETFs are tax-efficient compared to actively managed funds because they trade less frequently, generating fewer taxable events. Still, expect to owe taxes on gains in a taxable account. In a 401(k) or traditional IRA, you don't pay taxes until you withdraw; in a Roth IRA, you never pay taxes on gains if you follow the withdrawal rules.

If you're investing regularly over many years, the expense ratio and tax efficiency matter far more than trying to time the market or chase short-term gains. A 0.05% expense ratio difference might seem tiny, but over 30 years it can mean tens of thousands of dollars in your pocket instead of the fund company's.

What happens to your money over time

Once you own S&P 500 fund shares, their value changes every trading day based on what the 500 companies are worth. On days the market is up, your shares are worth more; on days it's down, they're worth less. This is normal and expected. The historical average return of about 10% per year includes years with 20% gains and years with 20% losses.

If you need the money in the next few years, the S&P 500 is not the right place for it — you might need to sell during a down year and lock in a loss. But if you're investing for 10, 20, or 30 years, short-term swings matter less because the long-term trend has historically been upward. Many investors who panic and sell during downturns end up worse off than those who hold steady.

You can check your account balance anytime online, but most investors benefit from checking infrequently — quarterly or annually — rather than daily. Watching the balance fluctuate daily often triggers emotional decisions that hurt returns.

Frequently Asked Questions

Do I need a lot of money to start investing in the S&P 500?

No. Most brokerages have no account minimums, and some S&P 500 funds have minimums as low as $1 or allow you to buy fractional shares. You can start with $100 or $500 and add more over time. The key is starting early so your money has time to grow.

Can I lose all my money investing in the S&P 500?

Extremely unlikely. For that to happen, all 500 large U.S. companies would need to fail simultaneously, which has never occurred in U.S. history. You can lose money in a given year or even over several years, but the historical record shows recovery and growth over longer periods. Past performance does not may provide future results.

Should I invest a lump sum or add money gradually?

Research suggests lump-sum investing historically outperforms dollar-cost averaging (adding gradually), but the difference is small. If a lump sum makes you anxious, adding money monthly is fine — the important thing is investing consistently and not trying to time the market.

What's the difference between an S&P 500 index fund and an S&P 500 ETF?

Both hold the same 500 companies and charge similar fees. Index funds trade once daily at a set price; ETFs trade throughout the day like stocks. ETFs offer slightly more flexibility if you want to sell mid-day, but for most long-term investors, the difference is negligible.

Do I have to reinvest the dividends?

Most brokerages automatically reinvest dividends by default, which compounds your returns over time. You can change this setting, but reinvesting is usually the better choice for long-term investors. Check your account settings to confirm.