You need a brokerage account, money to invest, and a decision about which index fund to buy

Investing in index funds means opening an account with a brokerage firm, depositing money, and buying shares of a fund that tracks a market index like the S&P 500. The process takes about 15 minutes to set up and costs nothing to start — you only pay when you buy or sell. Most brokerages let you start with as little as $1, though some index funds have a $500 or $1,000 minimum for the first purchase.

The three main steps are: open an account at a brokerage, move money into it, and place an order to buy the index fund you want. After that, the fund holds the shares and you can check your balance anytime. You do not need to do anything else unless you want to add more money or change your holdings later.

Key Takeaways

  • You must open an account at a brokerage firm like Fidelity, Vanguard, Charles Schwab, or Robinhood before you can buy any index fund.
  • The account setup takes 10 to 15 minutes and requires your Social Security number, address, and basic employment information.
  • You can fund your account by linking a bank account and transferring money, or by mailing a check — transfers usually clear within one to three business days.
  • Once money is in your account, you search for the index fund by its ticker symbol (like VOO or VTSAX) and place a buy order just like you would buy a stock.
  • Index funds charge an annual fee called an expense ratio, which ranges from 0.03% to 0.20% per year for most low-cost funds.

Choose a brokerage and open an account

A brokerage is a company that holds your money and lets you buy and sell investments. The major brokerages that offer index funds are Fidelity, Vanguard, Charles Schwab, E*TRADE, Robinhood, and Merrill Edge. Each one has a website and a mobile app. You do not need to pick the "best" one — they all work the same way for buying index funds, and the differences matter only if you plan to trade stocks frequently or want specific research tools.

Go to the brokerage's website and look for a button that says "Open an Account" or "get your free guide." You will enter your name, Social Security number, date of birth, address, and employment status. The brokerage will ask whether you want a regular taxable account (called a brokerage account) or a retirement account like an IRA. If you are not sure, start with a regular brokerage account — you can open a retirement account later. The whole process takes about 10 to 15 minutes, and you will get a confirmation email with your account number.

Link your bank account and deposit money

After your account opens, you need to move money from your bank into your brokerage account. Log in to your brokerage account and look for a button labeled "Deposit," "Fund Account," or "Transfer Money." You will be asked to link your bank account by entering your bank's name and your login details, or by providing your account and routing numbers. The brokerage will then verify the connection by depositing two small amounts (usually under $1 each) into your bank account — you confirm these amounts to prove you own the account.

Once your bank account is linked, you can transfer money whenever you want. Most transfers take one to three business days to arrive. Some brokerages also let you mail a check, though this is slower. Do not worry about timing the market perfectly — you can invest a small amount now and add more later.

Find the index fund you want to buy

Every index fund has a ticker symbol, a short code that identifies it. For example, VOO tracks the S&P 500, VTI tracks the entire U.S. stock market, and BND tracks U.S. bonds. If you came from the Index Fund FAQ, you already know which index you want to track. Now you need to find a fund that tracks it.

Log into your brokerage account and look for a search box or a "Buy" button. Type in the ticker symbol of the fund you want. The brokerage will show you the fund's name, current price, and expense ratio. Read the expense ratio carefully — it is the annual fee you pay, shown as a percentage. For example, 0.03% means you pay $3 per year for every $10,000 invested. Most index funds charge between 0.03% and 0.20% per year. If you see a fund with an expense ratio above 0.50%, it is probably not a low-cost index fund.

Place your first buy order

Once you have found the fund, click on it and you will see a screen that says "Buy" or "Trade." Enter the amount of money you want to invest or the number of shares you want to buy. Most brokerages let you choose either one — if you enter $500, the system calculates how many shares that buys; if you enter 10 shares, it shows you the cost. Then click "Review" or "Confirm," check that everything is correct, and click "Submit" or "Place Order."

Your order will go through when ready if the market is open (Monday through Friday, 9:30 a.m. to 4 p.m. Eastern time). If you place an order after hours or on a weekend, it will execute at the next market open. You will get a confirmation email with your order number and the number of shares you bought. The shares now belong to you and will show up in your account balance.

Understand what happens after you buy

Once you own shares of an index fund, you do not have to do anything. The fund automatically holds all the stocks or bonds in its index, and it rebalances itself to stay on track. You can check your account balance anytime by logging in to your brokerage. The balance will go up and down as the market moves, but you only lose money if you sell when the price is lower than what you paid.

If you want to add more money later, you can transfer it from your bank and buy more shares using the same process. If you want to sell some or all of your shares, you log in, find the fund, click "Sell," enter the number of shares or the dollar amount, and confirm. The money from the sale will land back in your brokerage account within one to three business days, and you can then transfer it back to your bank if you want.

Know the difference between taxable and retirement accounts

A regular brokerage account is taxable, meaning you owe taxes on any gains when you sell. A retirement account like a Traditional IRA or Roth IRA has tax advantages — you either get a tax deduction when you contribute (Traditional) or pay no taxes when you withdraw (Roth). Most brokerages let you open both types of accounts, and you can invest in index funds in either one.

If you are just starting out, a regular brokerage account is simpler because there are no contribution limits and no rules about when you can withdraw. A retirement account makes sense if you want to save for retirement and take advantage of the tax break. You can always open a retirement account later — there is no rush to decide now.

Frequently Asked Questions

Do I have to buy a whole share, or can I buy a fraction?

Most brokerages now let you buy fractional shares, meaning you can invest any dollar amount even if it does not add up to a whole share. For example, if an index fund costs $400 per share and you have $100 to invest, you can buy 0.25 shares. This makes it much easier to start with a small amount of money.

What is the difference between a fund and a stock?

A stock is a share of one company. An index fund is a basket of many stocks (or bonds) bundled together. When you buy an index fund, you own a tiny piece of every company in that index. This spreads your risk across many companies instead of betting on just one.

Can I set up automatic investments?

Yes. Most brokerages let you set up automatic transfers from your bank account on a schedule — weekly, monthly, or any interval you choose. The money transfers automatically, and you can set up a separate automatic buy order for the index fund so the money invests right away. This is called dollar-cost averaging and is a common way to invest over time.

What happens if the brokerage goes out of business?

Your investments are protected by the Securities Investor Protection Corporation (SIPC), which covers up to $500,000 per account at each brokerage. This means even if the brokerage fails, your shares and cash are yours — they will be transferred to another brokerage. SIPC protection is automatic; you do not have to do anything.

Can I move my index funds to a different brokerage later?

Yes. You can transfer your shares to another brokerage through a process called an ACAT transfer. You open an account at the new brokerage and request the transfer — the new brokerage handles most of the paperwork. The transfer usually takes five to seven business days and costs nothing or a small fee depending on the brokerage.