Diversification spreads investments to reduce overall risk. Instead of putting all your money in one stock, you buy many. Instead of one asset class, you hold several. The idea is simple: when one investment falls, another may rise. The losses do not cancel out entirely, but they are softened. The portfolio becomes less volatile.

Diversification works across several dimensions. Asset classes include stocks, bonds, real estate, and cash. Sectors include technology, healthcare, energy, and consumer goods. Geographies include domestic and international markets. Company sizes range from small caps to large caps. A well-diversified portfolio holds a mix. The mix depends on goals, time horizon, and risk tolerance. A young investor might hold mostly stocks. A retiree might favor bonds.

Diversification has limits. In a severe market crash, most assets fall together. Correlations rise during crises. Diversification cannot eliminate risk. It can only reduce the risk that comes from holding a single asset. It also cannot guarantee returns. A diversified portfolio will never be the top performer in any given year. It is designed to avoid being the worst. For most investors, that trade-off is worth it. The alternative is a wild ride with no safety net.

Key dimensions

• Asset classes
• Sectors
• Geographies
• Company sizes
• Time horizons