Expected value

The probability-weighted average profit or loss of a trade across every possible outcome — a positive expected value means the trade pays off on average when repeated many times.

Expected value is the probability-weighted average profit or loss of a trade across every outcome it can produce. You take each possible result, multiply it by the chance of that result happening, and add them all up. A positive expected value means the trade makes money on average when repeated many times under the same conditions; a negative one means it bleeds, no matter how good any single result looks. It is the single number that fuses payoff and probability into one honest verdict.

In practice it is the antidote to being fooled by either half of a trade in isolation. A cash-secured put that collects a small premium with a high probability of profit can carry a slim but positive expected value, while a lottery-ticket long call with a huge payoff can be negative because it wins so rarely. Working the numbers keeps you from chasing high win rates that hide oversized losses, or big payoffs that almost never land. It is the same engine behind return on risk and the Kelly criterion, just expressed in raw currency.

The common mistake is trusting an expected value built on made-up probabilities. The math is only as good as the win rate and payoffs you feed it, and in options those come from implied volatility and your own assumptions, both of which can be wrong. Expected value is also a long-run average, so a positive-EV trade can and will lose on any given day; it rewards you across many repetitions with disciplined sizing, not on a single roll of the dice.

← Back to the glossary · Guides · Strategies

All options terms

Educational use only. Quotes are delayed ~15 minutes and nothing here is financial advice. Options trading involves substantial risk of loss.