Where to Buy Index Funds: Your Main Options

The three places to buy index funds

You can buy index funds through a brokerage account, a retirement account, or directly from a fund company. Most investors use a brokerage because it takes minutes to open and you can buy almost any index fund available. A retirement account like a 401(k) or IRA limits your choices but offers tax advantages. Buying directly from a fund company works if you want to stick with one provider, but it is less flexible than a brokerage.

The choice depends on what you are saving for and whether you want tax breaks. If you are saving for retirement, a retirement account usually makes sense. If you are saving for something else — a house down payment, a car, a child's education — a regular brokerage account is the standard choice.

Key Takeaways

• A brokerage account lets you buy index funds from any provider and withdraw money whenever you want, with no tax penalty.
• A 401(k) through your employer or a traditional or Roth IRA for retirement offer tax advantages but restrict when you can withdraw money.
• You can buy index funds directly from fund companies like Vanguard, Fidelity, or Schwab, but you will have access only to their own funds.
• Opening an account at any of these takes 10 to 30 minutes online and requires basic identification and a bank account to fund it.
• The fees you pay vary by provider and fund, so comparing expense ratios across brokerages matters more than which brokerage you choose.

Brokerage accounts: the most flexible option

A brokerage account is a regular investment account with no special tax status. You open it at a brokerage firm — companies like Fidelity, Charles Schwab, E*TRADE, TD Ameritrade, or Interactive Brokers — and then buy and sell investments through that account. You can withdraw money whenever you want without penalty, and you can hold index funds from any provider.

The tradeoff is that you pay income tax on dividends and capital gains each year. If you hold an index fund for less than a year and sell it for a profit, you pay tax at your ordinary income rate. If you hold it for more than a year, you pay the lower long-term capital gains rate. Dividends from the fund are taxed as they are paid out, even if you reinvest them.

Opening a brokerage account takes about 15 minutes. You will need your Social Security number, a government ID, your address, and a bank account to link for deposits. Most brokerages let you start with any amount — some have no minimum, others ask for $1 to $500 to begin.

401(k) plans: employer-sponsored retirement accounts

If your employer offers a 401(k), you can contribute money directly from your paycheck before taxes are taken out. The money grows tax-free until you withdraw it in retirement. Many employers also match a portion of what you contribute — for example, they might add 50 cents for every dollar you put in, up to 6% of your salary. That match is assistance programs and a strong reason to use a 401(k) if one is available to you.

The downside is that you cannot withdraw the money before age 59½ without paying a 10% penalty plus income tax on the withdrawal. You also have limited choices — your employer picks which funds and index funds are available in the plan. Some 401(k)s offer a broad range of low-cost index funds; others offer only expensive options.

To enroll, contact your employer's human resources or benefits department. They will give you a list of available funds and show you how to choose your contributions. You decide what percentage of each paycheck goes into the plan, and the money is deducted automatically.

IRAs: retirement accounts you open yourself

An IRA (Individual Retirement Account) is a retirement account you open on your own, not through an employer. You can open one at any brokerage or fund company. There are two main types: a traditional IRA and a Roth IRA.

With a traditional IRA, you may deduct your contributions from your taxes in the year you make them, and the money grows tax-free. You pay income tax on withdrawals in retirement. With a Roth IRA, you contribute money after taxes, but the money grows tax-free and you pay no tax on withdrawals in retirement. A Roth is usually better if you expect to be in a higher tax bracket later; a traditional IRA is usually better if you are in a high bracket now.

Both types have the same withdrawal restriction as a 401(k): you cannot withdraw before 59½ without a 10% penalty and income tax, with limited exceptions. The contribution limit is the same for both types combined — $7,000 per year if you are under 50, or $8,000 if you are 50 or older (these limits change yearly). You can open an IRA and fund it by the tax filing deadline of the following year — usually April 15.

Buying directly from a fund company

You can open an account directly with a fund company like Vanguard, Fidelity, or Schwab and buy their index funds without using a brokerage. This works well if you want to invest in just one or two funds and do not plan to trade often. The process is the same as opening a brokerage account — you provide identification and link a bank account.

The limitation is that you can only buy that company's own funds. If Vanguard offers an S&P 500 index fund but you later want to switch to a different provider's version, you have to sell the Vanguard fund and buy the new one, which triggers a taxable event in a regular account. For this reason, most investors find it easier to use a brokerage account, where they can hold funds from multiple providers in one place.

How to compare costs across providers

The fee you pay to own an index fund is called the expense ratio. It is expressed as a percentage of your investment per year. An index fund with a 0.03% expense ratio costs $3 per year for every $10,000 you invest. An index fund with a 0.50% expense ratio costs $50 per year on the same $10,000.

The difference between providers matters less than the difference between funds. A low-cost S&P 500 index fund at Fidelity (0.03% expense ratio) costs almost the same as the same fund at Schwab or Vanguard. A high-cost S&P 500 fund at a different provider might charge 0.50% or more. When you are choosing where to open an account, look up the expense ratio of the specific index fund you want to buy, not just the brokerage name.

You can find expense ratios on the fund company's website or on financial data sites like Morningstar. Most major brokerages also list the expense ratio on the fund's detail page. Compare the ratios of the funds you are considering, and choose the lowest-cost option that is available at a brokerage you can easily access.

Getting started: the basic steps

First, decide what you are saving for and how long you have until you need the money. If it is for retirement and you have 10 or more years, a 401(k) or IRA is usually the better choice because of the tax advantages. If it is for something else, use a brokerage account.

Second, choose a provider. For a 401(k), your employer chooses the provider. For an IRA or brokerage account, you can pick any major brokerage — Fidelity, Charles Schwab, Vanguard, E*TRADE, and TD Ameritrade are all common choices. They all offer low-cost index funds and similar tools.

Third, open the account online. You will need your Social Security number, a government ID, your address, and a bank account to link. The process takes 10 to 30 minutes. Once your account is open, you can fund it by transferring money from your bank, and then you can buy the index fund you chose.

Frequently Asked Questions

Can I have both a 401(k) and an IRA at the same time?

Yes. You can contribute to both in the same year, but the tax deduction for a traditional IRA may be limited if you also have a 401(k) and earn above a certain income. A Roth IRA has no such limit. Check the IRS rules for your income level, or ask a tax professional.

What happens if I move to a new job with a different 401(k)?

You can leave the old 401(k) where it is, roll it into your new employer's 401(k) if they allow it, or roll it into a traditional IRA. A rollover moves the money without triggering taxes or penalties. Your old employer's benefits department or your new plan administrator can explain the rollover process.

Do I have to pick the same brokerage for an IRA and a regular account?

No. You can open a traditional or Roth IRA at one brokerage and a regular brokerage account at another. Many people keep them at the same place for simplicity, but there is no requirement to do so.

What is the minimum amount I need to start investing in index funds?

Most brokerages have no account minimum and let you buy a single share of an index fund, which might cost $50 to $500 depending on the fund. Some index funds have a minimum initial investment of $1,000 to $3,000, but you can usually avoid this by buying through a brokerage instead of directly from the fund company.

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

Yes, through a process called an ACAT transfer (Automated Customer Account Transfer). You open an account at the new brokerage and request they transfer your holdings from the old one. The transfer usually takes 5 to 10 business days and does not trigger taxes in a retirement account, though it may in a regular account if the funds have gained value.