Expectancy — the only number that matters
The Math of an Edge
What one trade is worth on average
Expectancy answers a single question: if I take this setup a hundred more times, what does each one earn me on average? The formula is plainer than it looks — (win rate × average win) minus (loss rate × average loss). Win 40% at $300 and lose 60% at $150: that's $120 minus $90, so every trade is worth $30 on average. Negative expectancy means the more you trade, the more you lose, and no amount of discipline fixes a strategy that is negative by design.