Hold a total market index fund as your core position

Own the whole market cheaply rather than trying to pick winning parts of it.

Why it works

Active fund management requires consistently outperforming a market that already aggregates all available information — an advantage that is theoretically impossible to sustain and empirically rare over long periods. An index fund that matches the market return, minus minimal fees, beats most active funds after costs simply because costs are lower and behavioral errors are smaller.

How to do it

1. Identify a total stock market or S&P 500 index fund with an expense ratio below 0.10%.
2. Direct your automatic contribution to this fund as the primary or sole equity holding.
3. Resist substituting thematic or sector funds — complexity here is the enemy, not the edge.

Evidence

SPIVA reports consistently show that 80–90% of actively managed US equity funds underperform their benchmarks over 10–15 year periods after fees. Vanguard founder John Bogle’s four decades of data support passive indexing as the default for individual investors. (observational)

Observational data on fund performance is robust; the claim does not guarantee that any specific future period will show the same pattern, though the fee arithmetic is structural.

Sources

• S&P SPIVA US Scorecard (annual reports, 2004–present)
• Bogle (2007), The Little Book of Common Sense Investing

Common mistake

Mixing index funds with actively managed funds or thematic ETFs "for diversification," which reintroduces costs and complexity without adding real diversification.