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🧠 Psychology·beginner

Gambler's Fallacy

The mistaken belief that past random events affect future random events — "I'm due for a win after 5 losses."

The gambler's fallacy is the false belief that past outcomes change the probability of future outcomes in independent events. The classic example: a coin lands heads 5 times in a row, so people bet on tails because it's "due." But each flip is independent — the probability of tails is still 50%, regardless of what came before. In trading, the gambler's fallacy shows up as "I've had 5 losers in a row, the next trade is bound to win." It's not. Each trade is independent. Past outcomes don't change the win rate of the next trade. The trader's edge per trade is exactly what it was before the streak started. The fallacy also runs the other way: "I've had 5 winners, I'm bound to lose the next one." Same error. Past wins don't increase the probability of a loss. The streak is just statistical noise around the underlying expectancy.
Real trade example

Casino gamblers betting on red after 8 blacks at a roulette wheel are committing the gambler's fallacy. The wheel doesn't remember what came before. Every spin is 47.4% red regardless.

Related terms

Recency Bias

intermediate

The tendency to give more weight to recent events than older ones — drives overreactions to fresh news and short-term noise.

Martingale

intermediate

A betting system where you double your size after every loss — mathematically destined to blow up the account eventually.

Anti-Martingale

intermediate

A position-sizing system where you INCREASE size after wins and DECREASE size after losses — the opposite of martingale.

Tilt

beginner

The emotional state where you're trading from anger, fear, or frustration instead of your plan — the precursor to blowing up your account.

Discipline

beginner

The ability to follow your trading plan exactly — without deviation — regardless of how you feel in the moment.

Revenge Trading

beginner

Taking impulsive trades immediately after a loss to try to "get back" — the #1 account killer in retail trading.

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