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Index funds are one of the simplest and most powerful ways to build wealth. They track a market index, charge very low fees, and have outperformed most actively managed funds over the long run. This guide shows you exactly how to start investing in index funds in 2026.
What Is an Index Fund?
An index fund is a type of investment fund that tracks a specific market index. The most common index is the S&P 500, which includes the 500 largest U.S. publicly traded companies. When you invest in an S&P 500 index fund, you own a tiny piece of all 500 companies.
Index funds do not try to beat the market. They simply match it. This sounds boring, but it works. Over any 20-year period in history, the S&P 500 has delivered positive returns. Most active fund managers fail to beat it consistently.
Why Index Funds Are So Popular
Low Fees
The average actively managed fund charges 0.60% to 1.0% per year. Leading index funds charge 0.03% to 0.10%. On a $100,000 portfolio over 30 years, that fee difference can cost you $100,000 or more in lost growth.
Instant Diversification
One S&P 500 index fund gives you exposure to 500 companies across every sector of the economy. You are not betting on one company or industry.
No Need to Pick Stocks
You do not need to research companies, read earnings reports, or guess which stocks will go up. The index does the work. You just own the market.
Consistent Long-Term Performance
The S&P 500 has averaged roughly 10% annual returns over the past 100 years, before inflation. That is not guaranteed, but it is a powerful historical track record.
Popular Index Funds to Consider
| Fund | What It Tracks | Expense Ratio | Ticker |
|---|---|---|---|
| Vanguard S&P 500 ETF | S&P 500 (500 large US companies) | 0.03% | VOO |
| Fidelity Zero Total Market | Total US stock market | 0.00% | FZROX |
| Schwab S&P 500 Index | S&P 500 | 0.02% | SWPPX |
| Vanguard Total Stock Market ETF | Total US stock market | 0.03% | VTI |
| Vanguard Total World Stock ETF | Global stocks (US + international) | 0.07% | VT |
Step-by-Step: How to Invest in Index Funds
Step 1: Open a Brokerage or Retirement Account
You need an account to hold your index funds. For retirement savings, open a Roth IRA or Traditional IRA at Fidelity, Vanguard, or Schwab. For taxable investing, open a regular brokerage account. All three are free to open with no account minimums.
For tax-free growth on your retirement savings, a Roth IRA is one of the best options. See our guide to How to Open a Roth IRA.
Step 2: Fund the Account
Link your bank account and transfer money in. You can start with as little as $1 at most brokerages. Many people set up automatic monthly contributions so they invest consistently without thinking about it.
Step 3: Search for Your Index Fund
Search by ticker symbol (e.g., VOO, VTI) or fund name. Read the fund summary to confirm it tracks the index you want and check the expense ratio.
Step 4: Place Your Buy Order
For mutual fund index funds, you place a dollar amount and the trade executes at end of day. For ETF index funds, you buy shares like a stock. Either works fine for long-term investors.
Step 5: Set Up Automatic Contributions
Consistency beats timing the market. Set up a recurring purchase (weekly or monthly) and let compound interest do the work over time.
Index Funds in a 401(k)
Many 401(k) plans offer index funds. Look for the fund with the lowest expense ratio in your plan, usually labeled as an S&P 500 index fund or total market index fund. If your plan has a target-date fund, that is also fine; it automatically adjusts its stock/bond mix as you approach retirement.
Common Mistakes to Avoid
Selling During Market Drops
Markets drop. Sometimes by 20% to 40%. This is normal. Investors who sell in panic lock in their losses. Investors who stay invested recover and grow. Do not sell during downturns unless you genuinely need the money.
Picking Too Many Funds
You do not need 10 index funds. One S&P 500 index fund or one total market index fund is enough for the core of most portfolios. Adding more funds often just creates complexity without meaningful diversification.
Checking Your Balance Every Day
Watching daily price swings can lead to emotional decisions. Check your balance monthly or quarterly. Then leave it alone.
How Much Should You Invest?
A common starting goal is to invest 15% of your gross income for retirement. If that is not possible now, start with 1% and increase by 1% each year. The key is to start. Time in the market matters more than the amount you invest at first.
Frequently Asked Questions
How much money do I need to start investing in index funds?
You can start with as little as $1 at Fidelity or Schwab. Vanguard mutual funds have a $1,000 minimum, but Vanguard ETFs have no minimum.
Can you lose money in an index fund?
Yes. Index funds can lose value when the market drops. However, diversified index funds have historically recovered over long time horizons.
Are index funds better than actively managed funds?
Over the long term, most actively managed funds underperform their benchmark index after fees. Index funds are the preferred choice for most long-term investors.
Rates as of May 2026. Rates change frequently. Verify current rates directly with each institution before applying.