Finance
Risk and Return
Higher returns require higher risk — fundamental investment principle
Risk and return are positively correlated in finance — higher expected returns require accepting higher risk. Risk-free rate: theoretical zero-risk (Treasury bills proxy). Risk premium: extra return for accepting risk. Risk types: market, credit, liquidity, inflation, currency, etc. Modern portfolio theory (Markowitz, Sharpe — Nobel laureates): diversification reduces risk without sacrificing return. Sharpe ratio: return per unit of risk. CAPM (Capital Asset Pricing Model): relationship between systematic risk (beta) and expected return. Foundation of: investment, finance, asset pricing.
- PrincipleHigher returns require higher risk
- Risk-free rateTreasury bills (proxy)
- Risk premiumExtra return for accepting risk
- MarkowitzDiversification reduces risk (Nobel 1990)
- Sharpe ratioReturn per unit of risk
- CAPMCapital Asset Pricing Model (Sharpe Nobel)
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Why risk-return matters
- Investment decisions. Foundation.
- Asset allocation. Risk-appropriate portfolios.
- Retirement planning. Long-term risk tolerance.
- Financial advising. Client recommendations.
- Capital allocation. Business investment.
- Risk management. Insurance, hedging.
- Education. Foundation of finance.
Common misconceptions
- Higher risk = higher returns guaranteed. Higher EXPECTED; not guaranteed.
- Diversification eliminates risk. Reduces; doesn't eliminate market risk.
- Past returns predict future. Doesn't always; major source of error.
- Beta = total risk. Just systematic risk.
- Higher beta always bad. Higher expected return too.
- Risk-free is risk-free. Inflation, sovereign risk possible.
Frequently asked questions
What's the risk-return trade-off?
Fundamental finance principle. Higher expected returns require accepting higher risk. Investors demand compensation for risk. Risk-free assets (T-bills): low return. Risky assets (stocks): higher expected return. Risk types. (1) Market risk: overall market movements. (2) Specific risk: individual security. (3) Inflation: erodes returns. (4) Liquidity: ease of selling. (5) Credit: counterparty default.
What's the risk-free rate?
Theoretical return on zero-risk asset. Proxy: short-term US Treasury bills. Backed by government. Default risk near zero. Long-term Treasuries: have interest rate risk (prices change with rates). Risk-free rate: foundation of asset pricing. Currently: ~5% (short-term, varies with monetary policy). Historic average: ~3-4% real.
What's a risk premium?
Extra return required to accept risk. Equity risk premium: historical ~5-8% above risk-free rate (varies by period). Compensation for: market volatility, individual stock risk, market downturns. Specific to asset class. High-yield bonds: 4-6% premium over Treasuries. Different markets: different premiums.
What's modern portfolio theory?
Harry Markowitz (1952, Nobel 1990). Diversification reduces risk without sacrificing returns. Holding multiple uncorrelated assets: portfolio volatility lower than weighted average. Optimization: efficient frontier (best return for given risk). Foundation of: indexing, asset allocation, asset management. Practical implication: don't put eggs in one basket.
What's the Sharpe ratio?
Return per unit of risk. (Return - Risk-free rate) / Standard deviation. Higher: better risk-adjusted return. Used to compare investments. Example. Stock with 12% return, 18% standard deviation: Sharpe ratio = (12 - 5)/18 = 0.39. William Sharpe Nobel 1990. Useful: comparing different return-risk profiles.
What's CAPM?
Capital Asset Pricing Model. Sharpe (1964). Expected return = Risk-free rate + Beta × (Market return - Risk-free rate). Beta: sensitivity to market movements. Beta = 1: moves with market. > 1: more volatile. < 1: less volatile. Predicts: required return based on systematic risk (beta). Foundation of asset pricing despite empirical limitations.
How is risk measured?
Several ways. (1) Standard deviation: total volatility. (2) Beta: systematic risk (correlation with market). (3) Value-at-Risk (VaR): worst-case loss within confidence interval. (4) Maximum drawdown: largest peak-to-trough decline. (5) Sortino ratio: like Sharpe but only downside volatility. Each captures different aspect. Combined: comprehensive risk picture.