Step 12
Level: intermediate
Sharpe Ratio measures the return in excess of the risk-free rate per unit of overall volatility. If measured incorrectly, investors can easily reward lucky decisions and punish correct decisions but encounter an unfavorable environment.
A high Sharpe indicates that the portfolio generated better returns relative to the volatility it endured. However, Sharpe assumes up and down volatility are both risky, and can be distorted by short data, assets that are rarely repriced, or strategies with tail risk. A single return number is not enough to conclude whether a strategy is good or bad.
By knowing where the returns came from, what risks were taken, and whether the results exceeded the benchmark, investors can improve the process instead of just reacting to the final result.
Sharpe Ratio measures the return in excess of the risk-free rate per unit of overall volatility.
Measuring performance is not just about showing off results. The goal is to understand whether the strategy worked as expected, whether the risk was worth it, and whether the results came from skill, environment, or luck. A portfolio with high returns but too much risk may not be as good as a more stable portfolio with lower returns and suitable for your goals.
A high Sharpe indicates that the portfolio generated better returns relative to the volatility it endured. However, Sharpe assumes up and down volatility are both risky, and can be distorted by short data, assets that are rarely repriced, or strategies with tail risk.
A performance metric always has a range of uses. CAGR does not indicate drawdown. Sharpe does not see all tail risks. The wrong benchmark leads to wrong conclusions. Attribution requires sufficiently good data. So use multiple complementary metrics instead of finding a single number to represent the entire quality of an investment.
Use Sharpe to compare similar strategies, but do not use it alone to draw safe conclusions.
During each review period, record the absolute return, return relative to the benchmark, drawdown, volatility and main drivers of performance. This helps you distinguish strategic issues from short-term noise, and detect early when the portfolio deviates from its original goals.
Choose the highest Sharpe strategy without considering drawdown, liquidity and tail risk.
A common mistake is to measure results in the way that is most favorable to the story you want to believe. Serious investors need to accept consistent metrics, appropriate benchmarks, and long enough data. Good measurement does not make the results better, but it makes the lessons clearer.
Return in excess of the risk-free rate divided by the standard deviation of return.
Yields with almost no credit risk in the same currency and term.
Returns are higher than the risk-free mark or benchmark.
There are measures of absolute returns, risk-adjusted returns, benchmark-relative returns, drawdowns, and return attribution.
Some metrics are used to compare strategies, some are used to understand investor experience, some are used to check risk.
Performance metrics depend on data quality, measurement period length, and benchmark suitability.
Application in performance measurement
A strategy that is consistently positive over many months may have a high Sharpe, but if leverage is used and there is a rare risk of collapse, the Sharpe does not sufficiently reflect the risk.
Risk performance analysis
Choose the highest Sharpe strategy without considering drawdown, liquidity and tail risk. This causes investors to draw the wrong lesson and can increase risks in the next cycle.
Changing the start or end date for better results compromises the integrity of the review.
Inappropriate benchmarking makes a portfolio appear better or worse than it actually is.
Choose the highest Sharpe strategy without considering drawdown, liquidity and tail risk. Returns are only meaningful when accompanied by volatility, drawdown, liquidity and targets.
Exercise 1 - reflection
Get portfolio results in the most recent 12 months and analyze them from a Sharpe ratio perspective.
Exercise 2 - case_study
A strategy that is consistently positive over many months may have a high Sharpe, but if leverage is used and there is a rare risk of collapse, the Sharpe does not sufficiently reflect the risk. Identify the correct conclusion, the likely wrong conclusion, and the additional data needed.
Exercise 3 - action_plan
Create a performance review sheet of 5 metrics you will track each quarter.