Diversification
Spreading investments across different assets to reduce risk without sacrificing expected returns.
What it means
Diversification is the strategy of spreading investments across different assets, sectors, geographies, or asset classes to reduce risk. The core principle: 'Don't put all your eggs in one basket.' When some investments decline, others may hold steady or rise, reducing overall portfolio volatility.
The math
The mathematical magic of diversification: as long as assets aren't perfectly correlated, combining them reduces total risk below what you'd expect from just averaging individual risks.
How to read it
- Systematic RiskCannot be diversified away - affects entire market
- Unsystematic RiskCan be eliminated through diversification
Worked example
Holding 30 stocks from different sectors eliminates most unsystematic risk. Adding international stocks and bonds further diversifies against country-specific and asset class risks.
In context
Diversification is called the 'only free lunch in investing' because it reduces risk without necessarily reducing expected returns. It's the most accessible risk management tool for individual investors.
Common mistakes to avoid
- Thinking owning many stocks in the same sector is diversification
- Ignoring that correlations increase during market crises
- Over-diversifying to the point of guaranteed mediocrity
Keep exploring
Correlation
Measures how two assets move together. Ranges from -1 (opposite) to +1 (identical). Key for diversification.
Modern Portfolio Theory (MPT)
Framework for constructing portfolios that maximize expected return for a given level of risk through diversification.
Efficient Frontier
The set of portfolios offering the highest expected return for each level of risk. Optimal portfolios lie on this curve.
Tracking Error
The standard deviation of the difference between portfolio returns and benchmark returns.
Capital Asset Pricing Model (CAPM)
A model relating expected return to systematic risk (beta). Foundation for understanding alpha and beta.
Articles
Portfolio Diversification Guide 2026: Build a Resilient Investment Portfolio
Master portfolio diversification in 2026. Learn how to spread risk across asset classes, sectors, and geographies to build a resilient investment portfolio that can weather any market.
Stock vs ETF: Which Is Right for Your Portfolio?
Compare stocks vs ETFs to determine which investment is right for your portfolio. Learn the key differences, pros and cons, and how to choose based on your goals.
See Diversification in action
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