How to Buy an S&P 500 Index Fund in Three Steps

You can buy an S&P 500 index fund through a brokerage account in about 15 minutes

An S&P 500 index fund tracks the 500 largest U.S. companies by market value. To own one, you open an account at a brokerage (a company that buys and sells investments on your behalf), deposit money, search for the fund by its ticker symbol, and click buy. The whole process takes less time than opening a bank account. You do not need to pick individual stocks, time the market, or have a large sum to start — most brokerages let you begin with $1 or $100.

The fund itself does the work: it automatically holds all 500 stocks in the right proportions, rebalances when the index changes, and charges you a small annual fee (typically 0.03% to 0.20% of what you own). You own your shares outright and can sell them whenever you want.

Key Takeaways

• Open a brokerage account at a company like Fidelity, Vanguard, Charles Schwab, or your bank, then link a bank account to deposit money.
• Search for an S&P 500 index fund by its ticker symbol (VOO, IVV, or SPLG are common ones) and place a buy order for the dollar amount you want to invest.
• The fund charges an annual fee that ranges from 0.03% to 0.20% depending on which fund you choose, and you pay it automatically from your account.
• You can buy as little as $1 worth at most brokerages, and you can sell your shares anytime the market is open without penalty.

Choose a brokerage where you will hold the fund

A brokerage is the intermediary between you and the stock market. You open an account there, deposit money, and use their platform to buy and sell investments. Most brokerages charge nothing to open an account and nothing per trade. The main differences are the user interface, customer service quality, and which funds they offer (though all major brokerages carry multiple S&P 500 index funds).

Common brokerages for individual investors include Fidelity, Vanguard, Charles Schwab, E*TRADE, and TD Ameritrade. Many banks also offer brokerage accounts. If you already have a checking account somewhere, starting there can be simpler because you already know how to log in and transfer money. If you are starting fresh, Fidelity and Vanguard are widely used and have strong reputations for low costs and customer support.

Once you have chosen a brokerage, visit their website or app and select "Open an Account" or "New Account". You will provide your name, address, Social Security number, and employment information. The process takes about 10 minutes. After you submit, the brokerage will verify your identity (usually instantly) and your account will be ready to fund.

Link your bank account and deposit money

After your brokerage account is open, you need to move money into it from your bank. Log into your brokerage account and look for "Deposit", "Fund Account", or "Transfer Money" — the exact wording varies by company. You will be asked to enter your bank's routing number and your account number, which you can find on a check or in your bank's app.

The brokerage will then initiate an electronic transfer (ACH transfer) from your bank to your brokerage account. This usually takes one to three business days. Some brokerages offer faster options like wire transfer, but ACH is free and standard. Once the money arrives in your brokerage account, it sits there as cash, ready to invest.

You do not have to deposit a large amount. Most brokerages let you invest as little as $1, and many have no minimum deposit at all. If you are new to investing, starting with a smaller amount you can afford to leave invested for years is a reasonable approach.

Search for the S&P 500 index fund and place your order

Now that you have cash in your brokerage account, you are ready to buy. Log into your account and look for a search box or a "Buy" button. You will search for the S&P 500 index fund by its ticker symbol — a short code that identifies the fund. Three of the most common S&P 500 index funds are VOO (Vanguard S&P 500 ETF), IVV (iShares Core S&P 500 ETF), and SPLG (SPDR Portfolio S&P 500 ETF). All three track the same index and have very low annual fees (around 0.03% to 0.04%).

Type the ticker symbol into the search box. The fund will appear with its name, current price, and annual fee (called the expense ratio). Click on the fund to open its details page. Then click "Buy" or "Trade". You will see a screen asking how much you want to invest. Enter the dollar amount (for example, $500 or $1,000) and confirm the order. The brokerage will calculate how many shares you get based on the current price and execute the trade immediately if the market is open, or at the market open the next trading day if you order after hours.

After the trade settles (usually one or two business days), the shares will appear in your account. You now own a piece of all 500 companies in the S&P 500. The fund will automatically reinvest any dividends the companies pay, and you can check your balance anytime by logging into your account.

Understand the annual fee and how it affects your returns

Every S&P 500 index fund charges an annual fee, called an expense ratio, which is a small percentage of the money you have invested. This fee pays for the fund company to maintain the fund, process trades, and handle customer service. The fee is deducted automatically from your account each year — you do not write a check or see a bill.

The expense ratio varies by fund and brokerage. Vanguard's VOO charges 0.03% per year, meaning if you invest $10,000, you pay $3 annually. iShares' IVV charges 0.04%, or $4 per year on the same $10,000. Some older or less popular S&P 500 funds charge 0.10% or higher. Over decades, even a difference of 0.06% compounds into thousands of dollars in lost returns, so choosing a low-cost fund matters.

You do not pay a separate trading fee to buy or sell the fund at most brokerages. Some brokerages may charge a commission on certain funds, but the major brokerages (Fidelity, Vanguard, Charles Schwab) do not. Always check the fund's details page before you buy to confirm the expense ratio and whether there is a trading fee.

Decide whether to invest a lump sum or add money over time

Once you own the fund, you can add more money whenever you want. Some investors deposit a large sum all at once. Others set up automatic monthly transfers from their bank account to their brokerage, then buy more shares of the fund on a regular schedule. Both approaches work — the choice depends on your cash flow and comfort level.

If you have a lump sum and are worried about timing the market (buying right before a drop), you can split it into smaller monthly purchases over several months or a year. This is called dollar-cost averaging. It does not may provide better returns, but it can reduce the anxiety of putting all your money in at once. Alternatively, research shows that investing a lump sum immediately, rather than waiting, tends to produce better long-term results on average — but only if you can afford to leave the money invested for years.

Most brokerages let you set up automatic monthly investments. Log into your account, find "Recurring Investment" or "Automatic Purchase", and enter the dollar amount and frequency. The brokerage will transfer that amount from your linked bank account and buy the fund on the date you choose, usually the first or fifteenth of each month.

Know when and how to sell your shares

You can sell your S&P 500 index fund shares anytime the stock market is open (Monday through Friday, 9:30 a.m. to 4 p.m. Eastern Time). There is no penalty for selling early, no holding period, and no fee at most brokerages. Log into your account, find the fund in your holdings, click "Sell", enter the number of shares or dollar amount you want to sell, and confirm.

The sale will execute immediately if you place the order during market hours, or at the market open the next trading day if you order after hours. The cash will appear in your brokerage account within one or two business days. You can then withdraw it to your bank account or use it to buy something else.

If you sell for more than you paid, you will owe capital gains tax on the profit. If you sell for less, you can deduct the loss from your taxes (subject to limits). These tax consequences are why many investors hold index funds for years in retirement accounts like a 401(k) or IRA, where the tax is deferred or eliminated. But in a regular taxable brokerage account, you are responsible for reporting the gains and losses on your tax return.

Frequently Asked Questions

What is the difference between VOO, IVV, and SPLG?

All three track the same S&P 500 index and hold the same 500 stocks. The main difference is the fund company: VOO is run by Vanguard, IVV by iShares (BlackRock), and SPLG by SPDR (State Street). Their expense ratios are nearly identical (0.03% to 0.04%), so the choice comes down to which brokerage you use and which platform you prefer. Most brokerages carry all three.

Can I buy an S&P 500 index fund inside a retirement account?

Yes. You can hold an S&P 500 index fund in a 401(k), IRA, Roth IRA, or other retirement account. Many employers offer S&P 500 index funds as an option in their 401(k) plan. If you have an IRA, you can open one at any brokerage and buy an S&P 500 index fund there. Holding the fund in a retirement account means you do not pay capital gains tax on the gains until you withdraw the money (or ever, in a Roth IRA).

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

No. The fund company rebalances automatically. When a company grows and becomes a larger share of the index, the fund adjusts its holdings to match. You do not have to do anything. If you own multiple types of investments (stocks, bonds, real estate), you may need to rebalance your overall portfolio, but the index fund itself handles its own rebalancing.

What happens if a company in the S&P 500 goes bankrupt?

The fund company removes it from the index and replaces it with another company that meets the S&P 500 criteria. Your shares are not worthless — the fund simply sells the bankrupt company's stock (usually for a loss) and buys the replacement. This happens automatically, and you do not have to do anything. Diversification across 500 companies means one bankruptcy has a tiny impact on your overall return.

Is there a minimum amount I have to invest?

Most brokerages have no minimum deposit and let you buy as little as $1 worth of an S&P 500 index fund. Some brokerages or funds may have a $100 or $1,000 minimum for the first purchase, but this is becoming rare. Check your brokerage's website or call customer service to confirm their minimum before you open an account.