Glossary
Diversification
Diversification is the practice of spreading investments across many holdings, asset types, and markets so that no single failure can do serious damage to the whole portfolio.
It works because different assets do not move in lockstep: in a year when one industry or country struggles, others may hold up. A broad index fund holding thousands of securities delivers wide diversification in a single purchase.
Why it matters in practice
Diversification is the one risk-management tool that does not require predicting anything. Its most common failure is illusory breadth — owning five funds that all hold the same large U.S. stocks, or holding a large slug of employer stock alongside a paycheck from the same company, doubling exposure to one firm's fortunes. Diversification limits downside but also guarantees the portfolio never matches its single best holding; that trade is the point.
Related terms: Asset Allocation · Index Fund · Volatility · Portfolio · Rebalancing