You can buy S&P 500 index funds through a brokerage account, either online or with a financial institution

An S&P 500 index fund tracks the 500 largest publicly traded companies in the United States. To own one, you open an account with a brokerage — a company that buys and sells investments on your behalf — then transfer money in and place an order for the fund. The fund itself is a pool of money managed to mirror the S&P 500's composition, so when you buy shares, you own a tiny piece of all 500 companies at once.

You do not need a financial advisor or special permission. Most brokerages let you open an account online in under an hour, and the minimum investment is often zero or very low. The fund sits in your account and grows as the underlying companies' stock prices rise.

The main choice is which brokerage to use. Common options include Fidelity, Vanguard, Charles Schwab, E-Trade, and Robinhood, though many others exist. Each charges different fees, offers different tools, and may have different minimum balances. Some are better for beginners; others cater to active traders.

Key Takeaways

  • You need a brokerage account to buy S&P 500 index funds; opening one takes minutes and usually costs nothing.
  • Different brokerages charge different fees and have different minimums, so comparing a few before you open an account saves money over time.
  • Once you own shares, you can hold them for years without doing anything, or set up automatic monthly deposits to buy more.
  • The fund's value will rise and fall with the stock market, and that movement is normal; selling during a downturn locks in losses.

Opening a brokerage account and choosing a fund

Start by picking a brokerage. Visit the website, look for "open an account" or "sign up," and follow the steps. You will need your Social Security number, a government ID, proof of address (usually a utility bill or bank statement), and your bank account details so you can transfer money in. The whole process usually takes 10 to 20 minutes.

Once your account is open, you will see a dashboard or homepage. Look for a search bar or a section labeled "invest," "trade," or "funds." Search for an S&P 500 index fund by name. Common ones include the Vanguard S&P 500 ETF (ticker: VOO), the Fidelity 500 Index Fund (FXAIX), and the Schwab U.S. 500 Index Fund (SWPPX). Each tracks the same 500 companies but may have slightly different fees.

The fee matters. It is called an expense ratio and is expressed as a percentage per year. A fund charging 0.03% costs $3 per year on a $10,000 investment. A fund charging 0.50% costs $50 on the same amount. Over decades, the difference compounds. Most S&P 500 index funds charge between 0.03% and 0.20%, so compare before you buy.

Depositing money and placing your first order

After you choose a fund, you need money in your account. Go to the "deposit" or "transfer funds" section and link your bank account. You will provide your routing number and account number, which you can find on a check or in your bank's app. The brokerage will verify the connection by depositing two small amounts (usually under $1) into your account, which you then confirm in your bank's system.

Once verified, transfer the amount you want to invest. This can be $100, $1,000, or more — there is no required minimum at most brokerages, though some funds themselves have minimums of $500 or $1,000. The transfer usually takes one to three business days to appear in your brokerage account.

When the money arrives, go back to the fund's page and click "buy," "invest," or "purchase." Enter the dollar amount or the number of shares you want. The brokerage will show you the current price per share and calculate how many shares your money will buy. Review the details, confirm, and submit. The order executes immediately during market hours (9:30 a.m. to 4 p.m. Eastern time on weekdays), or at the market open if you order after hours.

Setting up automatic investments

Many people buy once and hold for years. Others set up automatic recurring investments, where the brokerage withdraws a fixed amount from your bank account every month and buys more shares. This is called dollar-cost averaging and removes the guesswork of when to buy.

To set this up, look for "recurring investment," "automatic purchase," or "dividend reinvestment" in your account settings. Choose the fund, the dollar amount, and the frequency (weekly, monthly, or quarterly). The brokerage will handle the rest. You can pause or cancel anytime.

Automatic investing is useful because it forces consistency and removes emotion. You buy more shares when prices are low and fewer when they are high, which over time tends to lower your average cost per share.

Understanding what happens after you buy

Once you own shares, you do not have to do anything. The fund manager automatically adjusts the holdings to match the S&P 500, so if a company leaves the index or a new one joins, the fund rebalances without your involvement. You will see your account value change daily as the stock market moves. This is normal.

If the market drops 20%, your fund value drops 20%. If it rises 10%, your fund rises 10%. The fund does not protect you from losses, but it also does not amplify them — you own a piece of 500 companies, so no single company's failure destroys your investment.

Some funds pay dividends, which are small cash payments companies make to shareholders. When your fund receives dividends, the brokerage can either send you the cash or automatically reinvest it to buy more shares. Most people choose reinvestment because it compounds growth over time.

Fees and costs to watch

The expense ratio is the main ongoing cost. It is deducted automatically from the fund's value, so you never write a check for it — it just reduces your returns slightly each year.

Some brokerages also charge trading commissions when you buy or sell, though most major brokerages have eliminated these for index funds. Check the fund's details page before you buy to confirm the commission is zero.

If you sell shares later, you may owe capital gains tax on any profit. This is not a fee the brokerage charges; it is a tax you owe to the government. Long-term capital gains (on shares held over a year) are taxed at lower rates than short-term gains. Holding for years reduces your tax burden.

Choosing between an ETF and a mutual fund

S&P 500 index funds come in two forms: exchange-traded funds (ETFs) and mutual funds. Both track the same index and have similar expense ratios, but they work slightly differently.

ETFs trade like stocks — you buy and sell them during market hours at a price that changes throughout the day. Mutual funds are priced once per day, after the market closes, and all orders placed that day execute at the same price. For most people, this difference does not matter. ETFs are slightly more tax-efficient in taxable accounts, and mutual funds are simpler if you are setting up automatic monthly investments.

Popular ETFs include VOO (Vanguard), IVV (iShares), and SPY (SPDR). Popular mutual funds include FXAIX (Fidelity) and SWPPX (Schwab). All track the S&P 500 closely. Pick whichever brokerage you prefer and use their version.

Frequently Asked Questions

Do I need a lot of money to start?

No. Most brokerages have no minimum, and you can buy a single share of an S&P 500 index fund for the current price of that share — usually $300 to $500. You can start with $100 if you want. The smaller your starting amount, the longer it takes to grow, but starting early matters more than starting big.

What if the stock market crashes after I buy?

Your fund value will drop, but you have not lost money unless you sell. If you hold and keep investing, you will buy more shares at lower prices, which lowers your average cost. Historically, the market has recovered from every crash and reached new highs. Selling during a downturn locks in losses and is usually a mistake.

Can I withdraw my money whenever I want?

Yes. You can sell your shares anytime the market is open and transfer the cash back to your bank account within a few business days. There is no penalty for withdrawing early, though you may owe taxes on any gains. Some people treat index funds as long-term retirement savings and never touch them.

Which brokerage is best for beginners?

Fidelity, Vanguard, and Schwab are all beginner-friendly, have low or zero minimums, charge low fees, and offer good educational resources. Robinhood is simpler but has fewer tools. Pick one, open an account, and start. You can move your money later if you want.

Do I have to reinvest dividends?

No, but most people do. Reinvestment is automatic at most brokerages and compounds your growth over time. If you need the cash, you can choose to receive dividends as payments instead. Either way, you owe taxes on the dividends in the year you receive them.