Sharpe Ratio Explained: What It Means for Your Trading Strategy
A strategy that makes 100% with 50% volatility is better than one that makes 150% with 100% volatility. The Sharpe ratio proves this mathematically — and it's 40% of the composite score in the Strategy Lab.
What Is the Sharpe Ratio?
The Sharpe ratio measures risk-adjusted return — how much return you earn per unit of risk taken.
Sharpe = (Return − Risk-Free Rate) / Standard Deviation of Returns
In plain English: take your strategy's return, subtract what you'd earn risk-free (like a government bond), and divide by how volatile those returns were. The result tells you whether your returns came from skill or from taking excessive risk.
What the Numbers Mean
- ✗ Below 1.0: Poor. You're taking more risk than the return justifies.
- • 1.0–2.0: Acceptable. Most decent strategies live here.
- ✓ 2.0+: Excellent. High return relative to volatility.
- ✓ 3.0+: Exceptional. Rare in real-world trading.
Why It Matters More Than Raw Return
Strategy B made more money — but it took twice the risk to get there. Strategy A is the better risk-adjusted bet. Over time, compounding favours the strategy with the higher Sharpe because it loses less during drawdowns.
How TradeTestr Uses Sharpe
The Sharpe ratio is 40% of the composite score in the Strategy Lab — the heaviest weight of any metric. A setup with high return but low Sharpe (high volatility) gets penalised. A setup with moderate return but high Sharpe (smooth equity curve) ranks higher.
Limitations
- ✗ Assumes returns are normally distributed. Real markets have fat tails — extreme moves happen more often than normal distribution predicts.
- ✗ Backward-looking. A high historical Sharpe doesn't guarantee future performance.
- ✗ Doesn't capture tail risk. Two strategies can have the same Sharpe but very different worst-case scenarios.
That's why the Strategy Lab combines Sharpe with profit factor, Monte Carlo survival, and return % — no single metric tells the full story.