Win rate vs. expectancy: why a high win rate can still lose money

Here's a fact that surprises most new traders: you can win 90% of your trades and still go broke — and you can win just 40% and compound your account beautifully. The reason is that win rate, on its own, tells you almost nothing.

The number that actually matters

What matters is expectancy — your average outcome per trade, combining how often you win with how much you win versus lose:

Expectancy = (Win% × Average win) − (Loss% × Average loss)

A strategy is only worth trading if this number is positive after costs. Win rate is just one input.

How a 90% win rate loses

Imagine you win 90% of the time, but each win is small and each rare loss is enormous — you pick up pennies and occasionally lose a boulder. Nine small wins can be wiped out by one big loss. The win rate is dazzling; the expectancy is negative. This is the classic profile of strategies that "work" for months and then detonate (selling far out-of-the-money options can look like this).

How a 40% win rate wins

Now flip it: you're wrong most of the time, but your winners are several times the size of your losers. Lose small, often; win big, occasionally. The win rate looks bad, but the expectancy is positive — and positive expectancy, repeated with discipline, is what compounds.

Why this matters for how you trade

• Don't chase win rate. A high hit rate can hide a terrible risk/reward profile.
• Mind the size of wins vs. losses at least as much as their frequency. Cutting losers and letting winners run is, mathematically, an expectancy strategy.
• Judge a system by its expectancy and consistency, not by how often it feels good.

Winning often is pleasant. Winning on expectancy is profitable. They are not the same thing — and confusing them is one of the most expensive mistakes in trading.

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This article is educational and does not constitute investment advice or a recommendation. Options trading involves substantial risk and is not suitable for every investor. Autopilot Options does not guarantee profits or prevent losses. Past performance and historical data do not guarantee future results.