How to Start Investing in Index Funds

You can buy index funds through a brokerage account in three main ways: directly from a fund company, through an online broker, or through a workplace retirement plan

The easiest route for most people is opening an account at an online broker like Fidelity, Vanguard, Charles Schwab, or E*TRADE, then buying index fund shares the same way you would buy individual stocks. You fund the account with money from your bank, search for the index fund by its ticker symbol, and place an order. The whole process takes less than an hour.

If your employer offers a 401(k) or similar retirement plan, you can often buy index funds through that plan without opening a separate brokerage account. The money comes out of your paycheck before taxes, which is a significant advantage. A third option is buying directly from a fund company like Vanguard or Fidelity, but this is less common now because online brokers have made it unnecessary.

Key Takeaways

• Opening a brokerage account at an online broker takes 15 to 30 minutes and requires a Social Security number, proof of address, and a bank account to fund it.
• You can buy most index funds with no minimum investment at many brokers, though some funds set their own minimums ranging from $1,000 to $3,000.
• Workplace retirement plans often offer index funds with no trading fees and automatic payroll deduction, making them the cheapest way to invest if your employer offers them.
• Index funds charge an annual fee called an expense ratio, typically between 0.03% and 0.20%, which is deducted automatically from your account.
• You can start with as little as $100 to $500 at most brokers, though some offer fractional shares that let you invest any dollar amount.

Opening a brokerage account at an online broker

Choose a broker first. The major ones are Fidelity, Vanguard, Charles Schwab, E*TRADE, and Robinhood, though many others exist. They all offer index funds with low or no trading fees. Visit the broker's website and click the button to open an account — it is usually labeled "Open an Account" or "get your free guide".

You will need to provide your Social Security number, date of birth, address, and employment information. The broker will ask whether you want a taxable brokerage account or a retirement account (like a Roth IRA or traditional IRA). For most people starting out, a taxable brokerage account is simpler because there are no contribution limits and you can withdraw money anytime without penalty. If you are saving specifically for retirement, a Roth IRA or traditional IRA has tax advantages worth understanding separately.

Link a bank account so you can transfer money into your brokerage account. This usually takes one to three business days. Once the money arrives, you are ready to buy. Search for the index fund by its ticker symbol — for example, VOO for the Vanguard S&P 500 ETF or VTSAX for the Vanguard Total Stock Market Index Fund — and place an order just as you would for a stock.

Understanding minimums and fractional shares

Most online brokers have no account minimum, meaning you can open an account with $1. However, individual index funds sometimes set their own minimums. Mutual funds often require $1,000 to $3,000 to buy your first share, though some brokers waive this for retirement accounts. Exchange-traded funds (ETFs) have no fund-level minimum because you buy them one share at a time, and a single share might cost $50 to $400 depending on the fund.

Many brokers now offer fractional shares, which means you can buy a portion of a share. If an ETF costs $150 per share and you have $100 to invest, fractional shares let you buy 0.67 shares instead of waiting until you have $150. This removes the barrier to starting small. Check whether your chosen broker offers fractional shares — most do, but not all.

Using a workplace retirement plan

If your employer offers a 401(k), 403(b), or similar plan, you can often buy index funds through it. Log into your plan's website or app, usually through a link your employer provides, and look for the investment options. Most plans list 10 to 30 funds, and many include at least one broad index fund like an S&P 500 index fund or a total stock market index fund.

The advantage is automatic: money is deducted from your paycheck before taxes, reducing your taxable income for the year. You also avoid trading fees. The disadvantage is that you cannot withdraw the money before age 59½ without paying a penalty (with narrow exceptions). If you need access to the money sooner, a taxable brokerage account is better.

To start, contact your employer's benefits department or find the plan's website. You will fill out a form saying what percentage of your paycheck to contribute and how to split that money among the available funds. Many plans let you change this allocation quarterly or monthly.

Choosing which index funds to buy

The most common choice for a beginner is a total stock market index fund, which holds thousands of U.S. companies and tracks the entire market. Examples include VTSAX (Vanguard), FSKAX (Fidelity), and VTI (Vanguard ETF). These are simple, diversified, and require almost no decision-making after you buy.

If you want to add international stocks, look for a total international stock market index fund like VTIAX (Vanguard) or FTIHX (Fidelity). Many investors split their stock allocation 70% U.S. and 30% international, though this is a personal choice.

If you want to keep things even simpler, look for a target-date fund, which is an index fund that automatically adjusts its mix of stocks and bonds as you get closer to retirement. You pick the year you plan to retire, and the fund handles the rest. These are common in workplace plans and are a good choice if you do not want to think about rebalancing.

What to expect in terms of costs

Index funds charge an annual fee called an expense ratio, expressed as a percentage of your investment. A 0.10% expense ratio means you pay $10 per year for every $10,000 invested. This fee is deducted automatically from your account and is already reflected in the fund's price — you do not write a check for it.

Most index funds charge between 0.03% and 0.20% per year. Vanguard and Fidelity typically charge on the lower end. Some brokers also charge trading fees when you buy or sell, but most major brokers have eliminated these fees for stocks and ETFs. Mutual funds sometimes still charge trading fees, so check before you buy.

Beyond the expense ratio, you may owe capital gains taxes if you sell the fund for more than you paid, though this happens only in taxable accounts, not in retirement accounts. Index funds are tax-efficient compared to actively managed funds because they trade less frequently, so this is usually a small cost.

Setting up automatic investing

Most brokers let you set up automatic transfers from your bank account on a schedule — weekly, monthly, or quarterly. This is called dollar-cost averaging and removes the temptation to time the market. Instead of trying to guess when to invest a lump sum, you invest the same amount regularly regardless of whether the market is up or down.

To set this up, go to your broker's settings and look for "automatic investment" or "recurring transfer". You will specify the amount, the frequency, and which fund to buy. Some brokers also let you set up automatic reinvestment of dividends, which means any cash the fund pays out is automatically used to buy more shares.

Frequently Asked Questions

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

No. Most online brokers have no account minimum, and fractional shares let you invest any dollar amount. You can start with $100, $500, or whatever you have. Workplace retirement plans often have no minimum either. The key is starting, not the size of your first investment.

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

Both track an index, but they trade differently. Mutual funds are priced once per day after the market closes, and you buy them directly from the fund company. ETFs trade throughout the day like stocks and often have lower expense ratios. For most beginners, ETFs are simpler because you can buy fractional shares and there is no fund minimum.

Can I lose money investing in index funds?

Yes. Index funds track the market, so if the market falls, your investment falls too. Over long periods (10+ years), stock market index funds have historically recovered from downturns, but there is no may provide. If you need the money in the next few years, index funds may not be appropriate.

Should I invest in a taxable account or a retirement account?

If your employer offers a 401(k) match, contribute enough to get the full match first — that is assistance programs. After that, a Roth IRA is often better than a taxable account because withdrawals in retirement are tax-free. Once you have maxed out retirement accounts, a taxable brokerage account is the next step.

How often should I check my index fund investment?

Once or twice a year is enough. Index funds are designed to be held long-term, and checking daily or weekly often leads to panic selling during downturns. If you set up automatic investing and reinvestment of dividends, you can largely ignore your account between annual check-ins.