An index fund holds all the stocks or bonds in a market index, such as the S&P 500, aiming to match its performance rather than beat it.
Why people choose them
Index funds offer instant diversification, very low costs and tax efficiency. Over long periods, the majority of actively managed funds have trailed their benchmark index after fees, which is a strong argument for a simple approach.
How to get started
Open an account such as an IRA, a 401(k) or a brokerage account. Choose a broad fund, such as a total US stock market or total world fund, and consider a bond index fund to balance risk. Many brokers offer funds with expense ratios under 0.10%.
Common beginner mistakes
Trying to time the market, chasing last year's winners, ignoring fees and panic-selling in downturns. Set up automatic monthly investments, rebalance annually and keep a long-term perspective.
Try the numbers
Use our Investment Fee Calculator to see this in practice. With its default example (Starting balance: $50,000; Monthly contribution: $1,000; Gross annual return: 7.5%), it shows lost to higher fees: $342,372. Adjust the inputs to match your situation.
Key takeaways
- Index funds are cheap, diversified and simple.
- Look for expense ratios below 0.10% for broad funds.
- Invest regularly and avoid market timing.
This article is for general education and is not personalized financial, tax or legal advice. Rules and limits change; confirm current figures with official sources such as IRS.gov, SSA.gov and StudentAid.gov, or consult a qualified professional. © 2026 FinanzCalc.