You can buy index funds through a brokerage account, a retirement account, or directly from a fund company

The place you buy an index fund depends on what account type you want to use and which fund company appeals to you. Most people open a brokerage account with a firm like Fidelity, Charles Schwab, or Vanguard, then purchase index funds through that account. You can also buy index funds inside a 401(k) or IRA if your employer or bank offers them. A third option is to go directly to a fund company's website and open an account there, though this limits you to that company's funds only.

The mechanics are straightforward: you open an account, fund it with money from your bank, search for the index fund you want by its ticker symbol, and place an order. The fund company then holds your shares. There are no special requirements or paperwork beyond what any brokerage account needs.

Key Takeaways

  • Brokerage firms like Fidelity, Charles Schwab, and Vanguard let you buy index funds from many different fund companies in one account.
  • Opening a brokerage account takes 10 to 20 minutes online and requires your Social Security number, address, and bank details for funding.
  • If you have a 401(k) through your employer, you may already have access to index funds without opening a separate account.
  • Index funds have no minimum purchase amount at most brokerages, though some fund companies require $1,000 or $3,000 to start.
  • You pay no commission to buy or sell index funds at major brokerages, though the fund itself charges a small annual fee.

Opening a brokerage account at a major firm

A brokerage account is the most common way to buy index funds. The three largest firms are Fidelity, Charles Schwab, and Vanguard, but E-Trade, TD Ameritrade, and Merrill Edge also offer index funds. Each firm holds your money and your shares, and you can buy index funds from multiple fund companies within the same account.

To open an account, go to the firm's website and click the button to open a new account. You will enter your name, address, Social Security number, and employment information. You will also choose whether you want a taxable brokerage account (for money you do not plan to retire with) or a tax-advantaged account like a Roth IRA or traditional IRA. The whole process takes 10 to 20 minutes. Once your account is open, you link a bank account so you can transfer money in.

After your first deposit clears—usually one to three business days—you can search for an index fund by its ticker symbol (for example, VOO for Vanguard's S&P 500 index fund) and place an order. You will see the fund's current price and can buy as many shares as your account balance allows. There is no commission charge at any of these major firms.

Buying index funds through your employer's 401(k)

If your employer offers a 401(k) plan, you may already have access to index funds without opening a separate account. When you enroll in your company's 401(k), you choose how much of your paycheck to contribute, and the plan administrator shows you the investment options available. Many plans include at least one S&P 500 index fund or a target-date fund (which is a mix of index funds chosen for your retirement year).

The advantage of a 401(k) is that contributions come straight from your paycheck before taxes, which lowers your taxable income that year. Some employers also match a portion of what you contribute. The disadvantage is that you can only choose from the funds your employer's plan offers—you cannot buy any index fund you want the way you can in a brokerage account.

To see what index funds are available in your plan, log into your 401(k) account online or ask your HR department for the plan's investment menu. If your plan does not offer index funds, you can still open a separate brokerage account and buy them there with money outside your 401(k).

Buying index funds through an IRA

An IRA is a retirement account you open on your own, not through an employer. You can open a traditional IRA or a Roth IRA at any brokerage firm—Fidelity, Schwab, Vanguard, or others. The process is the same as opening a regular brokerage account, except you tell the firm you want an IRA instead of a taxable account.

The main benefit of an IRA is the tax advantage: contributions to a traditional IRA may be tax-deductible, and earnings in a Roth IRA grow tax-free. The catch is that you cannot withdraw money before age 59½ without a penalty (with some exceptions). For 2024, you can contribute up to $7,000 per year to an IRA if you are under 50, or $8,000 if you are 50 or older. These limits change each year.

Once your IRA is open and funded, you buy index funds the same way you would in a regular brokerage account—search by ticker symbol and place an order. Many people use both a 401(k) and an IRA to save for retirement, since each has its own contribution limit.

Buying directly from a fund company

You can also open an account directly with a fund company like Vanguard, Fidelity, or Schwab and buy only that company's index funds. This works if you have decided on one fund company and do not plan to buy from others. The account opening process is the same as with a brokerage, and you can still buy and sell as often as you want.

The downside is that you are limited to one company's offerings. If you later want to buy an index fund from a different company, you would need to open a second account. Most people find it simpler to open one brokerage account and have access to funds from all major companies in one place.

Some fund companies also set a minimum initial investment—Vanguard, for example, requires $1,000 to open most of its index funds, though some have no minimum. Check the fund company's website for its specific rules before you open an account.

Understanding account types and tax treatment

The account type you choose affects how your money is taxed. A taxable brokerage account has no contribution limits and no withdrawal restrictions, but you pay taxes on any gains when you sell. A traditional IRA lets you deduct contributions from your taxes now, but you pay taxes on withdrawals in retirement. A Roth IRA has no tax deduction now, but withdrawals in retirement are tax-free.

A 401(k) works like a traditional IRA in that contributions are pre-tax, but your employer controls which funds are available. If you are saving for retirement, most financial advisors suggest maxing out your 401(k) first (especially if your employer matches), then opening an IRA if you have more to invest, then using a taxable brokerage account for anything beyond that.

The good news is that you do not have to choose just one. Many people have a 401(k) at work, an IRA for additional retirement savings, and a taxable brokerage account for shorter-term goals. You can buy the same index fund in all three accounts if you want.

Comparing costs across brokerages

All major brokerages charge zero commission to buy or sell index funds, so the cost difference between them is small. What matters more is the expense ratio of the index fund itself—the annual fee the fund company charges to manage it. This fee is the same no matter where you buy the fund.

For example, Vanguard's S&P 500 index fund (VOO) has an expense ratio of 0.03%, meaning you pay $3 per year for every $10,000 invested. Fidelity's equivalent fund (FXAIX) charges 0.015%, and Schwab's (SWPPX) charges 0.03%. These differences are tiny, but they add up over decades. You can compare expense ratios on any brokerage's website before you buy.

Some brokerages offer slightly better tools or customer service, but for buying index funds, the differences are minor. Pick whichever firm has a website you find straightforward to use or customer service you trust. You can always move your funds to a different brokerage later if you change your mind.

Frequently Asked Questions

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

No. Most brokerages have no minimum to open an account or buy index funds. Some fund companies require $1,000 or $3,000 to start, but you can avoid this by buying through a brokerage instead. You can start with $100 or $500 if that is what you have.

Can I buy the same index fund at different brokerages?

Yes. The same index fund is available at multiple brokerages. For example, Vanguard's S&P 500 fund (VOO) can be bought at Fidelity, Schwab, or directly from Vanguard. The fund itself is identical; only the account you hold it in differs.

What happens if a brokerage goes out of business?

Your money is protected by the Securities Investor Protection Corporation (SIPC), which insures up to $500,000 per account at each brokerage. Your index fund shares would be transferred to another brokerage. This has never happened with a major firm like Fidelity or Schwab, but the protection exists.

Can I move my index funds from one brokerage to another?

Yes. You can transfer your shares to a different brokerage through a process called an ACAT transfer. The new brokerage handles most of the paperwork. There is usually no fee, though it takes five to seven business days to complete.

Should I buy index funds in a 401(k) or a brokerage account?

If your employer offers a 401(k) match, contribute enough to get the full match first—that is information programs. After that, it depends on your situation. A traditional or Roth IRA offers more fund choices and lower fees. A taxable brokerage account has no limits on how much you can invest or when you can withdraw.