Angel Investors Network
    Glossary

    Sharpe Ratio

    A measure of risk-adjusted return calculated by dividing the excess return over the risk-free rate by the standard deviation of returns.

    The Sharpe Ratio is a metric that measures risk-adjusted returns by dividing an investment's excess return (above the risk-free rate) by its standard deviation. Named after Nobel laureate William F. Sharpe, this ratio helps investors understand whether returns compensate adequately for the volatility endured.

    The formula is straightforward: subtract the risk-free rate (typically U.S. Treasury yields) from the portfolio's average return, then divide by the standard deviation of returns. A ratio of 1.0 means the investment earned one unit of return for each unit of risk. Values above 2.0 are considered excellent, while anything below 1.0 suggests poor risk-adjusted performance. A negative Sharpe Ratio indicates the investment underperformed even risk-free alternatives.

    Why It Matters

    Angel investors face enormous volatility in startup portfolios, where individual companies might return 10x or lose everything. The Sharpe Ratio provides a quantitative framework to compare opportunities across different risk profiles. A high-flying tech startup generating 40% annual returns with 60% volatility (Sharpe Ratio of 0.63, assuming 2% risk-free rate) might actually deliver worse risk-adjusted returns than a stable SaaS company returning 25% with 20% volatility (Sharpe Ratio of 1.15). This comparison prevents investors from chasing returns without accounting for sleepless nights.

    Example

    Consider two angel investors evaluating their 2023 portfolio performance. Investor A backed five enterprise software companies, achieving 28% returns with 15% standard deviation. With a 4% risk-free rate, their Sharpe Ratio is (28% - 4%) / 15% = 1.6. Investor B pursued moonshot biotech deals, earning 45% returns but with 50% volatility, producing a Sharpe Ratio of (45% - 4%) / 50% = 0.82. Despite Investor B's higher absolute returns, Investor A achieved superior risk-adjusted performance. Over a 10-year horizon, Investor A's approach would likely prove more sustainable and psychologically manageable, particularly during market downturns when volatile portfolios experience severe drawdowns.

    Standard Deviation, Portfolio Diversification, Risk-Adjusted Return