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Index Fund

In short

Fund that tracks a market index — low cost, passive, market returns

An index fund automatically owns every stock in an index (like the S&P 500). No stock picking. Very low fees. You get the market's return. Studies show 80-90% of active fund managers underperform index funds over 15 years.

Index funds replicate index composition and weights. Total market index funds offer maximum diversification. Low expense ratios (0.03-0.20%) vs active funds (0.5-1.5%) compound to massive savings over decades. Warren Buffett recommends index funds for most investors.

Related concepts

  • ETF (Exchange-Traded Fund) — An ETF is like a basket of stocks that trades on the stock exchange just like a share. Buy one ETF and you might own 500 companies. They combine the diversification of mutual funds with the trading flexibility of stocks.
  • Passive Investing — Passive investing means buying index funds and holding them forever. No stock picking, no market timing. You get exactly what the market returns, minus tiny fees. Research consistently shows it beats most active strategies over the long run.
  • Benchmark — A benchmark is your measuring stick. If you earned 12% but the S&P 500 (your benchmark) earned 15%, you actually underperformed despite making money. Most active managers struggle to consistently beat their benchmark.
  • Diversification — If you put all your money in one stock and it crashes, you lose everything. Spread it across 20 different stocks, sectors, and even countries — when one falls, others may rise, protecting your overall wealth.