What is an Index Fund?
An index fund passively tracks a market index like the S&P 500 by holding the same stocks in the same proportions. Vanguard's S&P 500 index fund (VFIAX) charges just 0.04% annually and holds all 500 companies. Over the past 15 years, approximately 90% of actively managed large-cap funds have underperformed the S&P 500 index.
Why Index Funds Work
Index funds succeed because of low costs, broad diversification, and tax efficiency. The average actively managed fund charges 0.60-1.00% in fees, while index funds charge 0.03-0.20%. That fee difference compounds dramatically over decades. A total world stock index fund provides exposure to over 9,000 companies across 40+ countries in a single investment.
Key Considerations
Index funds guarantee market-average returns minus minimal fees, which beats most alternatives over time. However, they provide no downside protection during bear markets - you will experience the full decline. For most investors, a simple portfolio of 2-3 index funds covering global stocks and bonds is sufficient for long-term wealth building.