How to start investing in index funds

To invest in index funds, you open a brokerage account, deposit money, search for the index fund you want by its ticker symbol, and place a buy order. The whole process takes about 15 minutes once your account is open. The account opening itself — providing your name, address, Social Security number, and employment information — usually takes 10 to 20 minutes online and can be done through a bank, a discount brokerage firm like Fidelity or Vanguard, or a robo-advisor platform.

The money you deposit sits in your account until you use it to buy. You do not have to spend it all at once. Many people set up automatic monthly transfers so money moves into their brokerage account on the same day each month, then they use that money to buy index funds on a schedule that works for them.

Index funds are bought and sold just like individual stocks. You enter the fund's ticker symbol — a short code like SPY, VOO, or VTI — into your brokerage's search box, see the current price, decide how many shares you want, and confirm the purchase. The transaction settles in one to two business days, meaning the shares appear in your account and the money leaves your cash balance.

Key Takeaways

  • Opening a brokerage account requires your name, address, Social Security number, and employment information, and takes 10 to 20 minutes online.
  • You deposit money into the account first, then use that cash to buy index fund shares by searching for the fund's ticker symbol.
  • Different account types — taxable brokerage, IRA, 401(k) — have different tax treatment and contribution limits, so the account you choose matters as much as the fund itself.
  • Index funds charge an annual fee called an expense ratio, typically between 0.03% and 0.20% per year for passively managed funds.
  • You can buy index funds through a traditional brokerage, a robo-advisor that automates purchases, or directly through some fund companies like Vanguard.

Choosing the right account type for your situation

The account you open determines how your gains are taxed and how much you can contribute each year. A taxable brokerage account has no contribution limits and no restrictions on when you withdraw money, but you pay capital gains tax on profits when you sell. An IRA (Individual Retirement Account) lets you contribute up to $7,000 per year (or $8,000 if you are 50 or older), and you pay no tax on gains inside the account — but you cannot withdraw before age 59½ without a penalty, except in narrow circumstances. A 401(k) through your employer works similarly to an IRA but with higher contribution limits (up to $23,500 per year in 2024, or $31,000 if you are 50 or older) and often includes employer matching money.

If you have access to a 401(k) with employer matching, that is usually the first place to invest because the match is when ready, may provide money. After that, many people max out an IRA, then use a taxable account for anything beyond that. If you do not have a 401(k) available, an IRA is typically the next step because the tax deferral compounds over decades.

The type of IRA also matters. A Traditional IRA lets you deduct contributions from your taxable income in the year you make them (if you meet income limits), but you pay income tax on withdrawals in retirement. A Roth IRA takes contributions after tax, but withdrawals in retirement are tax-free. Which one makes sense depends on whether you expect your tax bracket to be higher or lower in retirement — something you cannot know for certain, which is why many people use both.

Finding and comparing index funds before you buy

Once you have chosen an account type, you need to decide which index funds to buy. Start by identifying which index you want to track — the S&P 500 (large US companies), the total US stock market, international stocks, bonds, or some combination. Then search your brokerage for funds that track that index. Multiple fund companies offer funds tracking the same index, and they charge different fees.

For example, three major funds all track the S&P 500: the Vanguard S&P 500 ETF (ticker VOO), the iShares Core S&P 500 ETF (ticker IVV), and the SPDR S&P 500 ETF (ticker SPY). All three hold the same 500 companies in the same proportions. The difference is the expense ratio — the annual fee charged as a percentage of your investment. VOO charges 0.03% per year, IVV charges 0.03%, and SPY charges 0.09%. On a $10,000 investment, that is $3, $3, and $9 per year respectively. Over decades, that small difference compounds.

Your brokerage will show you the expense ratio, the fund's holdings, and its performance history when you search for it. You do not need to read every document, but the expense ratio and the index it tracks are the two things worth comparing across options. Lower expense ratios are better, all else equal, because more of your money stays invested instead of going to fees.

Setting up automatic investing to build discipline

Many investors set up automatic investment plans where money transfers from their bank account to their brokerage on a fixed schedule — usually monthly or biweekly — and then automatically buys a set index fund. This removes the decision-making from the process and ensures you invest consistently regardless of market conditions.

To set this up, you link your bank account to your brokerage, set up a recurring transfer for the amount you want to invest, and then create a standing order to buy a specific index fund with that money on the same day the transfer arrives. Some brokerages call this a "systematic investment plan" or "automatic purchase plan." The exact steps vary by brokerage, but the concept is the same: money flows in, gets invested, and you do not have to think about it.

This approach works because it forces you to invest in both up markets and down markets. When prices are high, you buy fewer shares. When prices are low, you buy more shares. Over time, this smooths out the impact of market timing and removes the emotional pressure to buy high or sell low.

Understanding costs: expense ratios and trading fees

Index funds charge two types of costs: the expense ratio and any trading fees your brokerage charges. The expense ratio is built into the fund's price and is deducted automatically. Most index funds charge between 0.03% and 0.20% per year. A fund with a 0.05% expense ratio costs $5 per year on a $10,000 investment.

Trading fees are separate and depend on your brokerage. Most major brokerages — Fidelity, Vanguard, Charles Schwab, E-Trade — charge zero commission to buy or sell stocks and ETFs, meaning you pay no fee to place the order itself. Some smaller or older brokerages still charge per-trade fees, typically $5 to $10 per transaction. If your brokerage charges per-trade fees, that cost matters more when you are making small purchases, because a $10 fee on a $100 investment is much steeper than a $10 fee on a $5,000 investment.

When comparing brokerages, look for zero-commission trading on stocks and ETFs. The expense ratio of the fund itself is more important than the brokerage fee because you pay it every year for as long as you hold the fund, while the trading fee is a one-time cost.

Tax considerations for different account types

The tax treatment of index fund gains depends entirely on the account you use. In a taxable brokerage account, you owe capital gains tax when you sell a fund at a profit. If you held the fund for more than one year, you pay long-term capital gains tax, which is usually lower than your ordinary income tax rate (0%, 15%, or 20% depending on your income). If you held it for less than one year, you pay short-term capital gains tax at your ordinary income tax rate. You also owe tax on any dividends the fund distributes, even if you reinvest them.

In a Traditional IRA or 401(k), you pay no tax on gains or dividends while the money is in the account. You pay income tax only when you withdraw money in retirement. In a Roth IRA, you pay no tax on gains or withdrawals ever — the money grows tax-free and comes out tax-free in retirement.

This is why account type matters so much. An index fund held in a Roth IRA for 30 years grows completely tax-free. The same fund in a taxable account means you owe tax on gains every year you hold it, which reduces the amount available to compound. For long-term investing, tax-advantaged accounts almost always outpace taxable accounts.

Getting money into your account and placing your first order

After you open your account, you need to fund it. Most brokerages let you link your bank account and transfer money electronically. This usually takes one to three business days to clear. Some brokerages also accept wire transfers (faster but may have fees) or checks (slower). Once the money appears in your account as available cash, you can buy.

To place your first order, log into your brokerage, search for the index fund by its ticker symbol, and click on it. The fund's page will show the current price per share, the expense ratio, and other details. Enter the number of shares you want to buy (or the dollar amount, and the brokerage will calculate shares for you), review the order, and confirm. The order executes at the next market close if you place it during market hours, or at the next market open if you place it after hours.

After the order settles — usually one to two business days — the shares appear in your account and the cash balance decreases. You now own index fund shares. From that point forward, you can hold them, add to them, or sell them whenever you want (though selling in a taxable account triggers a tax event).

Frequently Asked Questions

Do I need a lot of money to start investing in index funds?

No. Most brokerages have no minimum deposit requirement. You can open an account and buy a single share of an index fund if you want. Starting small and investing regularly over time builds wealth just as effectively as starting with a large lump sum, because compound growth works on whatever amount you have.

What is the difference between an index fund and an ETF?

An index fund is any fund that tracks an index. An ETF (exchange-traded fund) is a type of index fund that trades on a stock exchange like a stock, meaning you can buy and sell it during market hours at a changing price. A mutual fund is another type of index fund that trades only once per day at a fixed price. Both track indexes, but ETFs are more flexible for frequent trading and often have lower expense ratios.

Can I lose money investing in index funds?

Yes. Index funds track the overall market, so if the market falls, the fund's value falls too. However, index funds are diversified across many companies, so a single company's failure does not wipe out your investment. Over long periods — 10 years or more — stock market index funds have historically recovered from downturns, but there is no may provide.

Should I invest a lump sum all at once or spread it out over time?

Research shows that lump-sum investing — putting all the money in at once — historically outperforms dollar-cost averaging (spreading purchases over months) because markets tend to rise over time. However, dollar-cost averaging reduces the anxiety of timing the market and works better psychologically for many people. Either approach works if you stay invested for the long term.

How often should I buy index funds?

That depends on your income and goals. If you are setting up automatic monthly investments, you buy monthly. If you are investing a bonus or tax refund, you buy when you have the money. The frequency matters far less than the total amount you invest over time and how long you stay invested. Buying consistently, even in small amounts, compounds into significant wealth over decades.