Anti-martingale - GetProfitable

Anti-martingale is the mirror of martingale: bet more when you are winning, less when you are losing. fixed-fractional-sizing is an anti-martingale by construction, since risk is a percentage of a rising or falling balance.

Its virtue is survival. Losing streaks shrink the bet geometrically, so the account decays slowly rather than dying suddenly, and winning streaks compound. The cost is a lumpier equity curve and slower recovery from drawdown, because size is smallest during the rebound.

A crude but useful version: risk 1% normally, drop to 0.5% after a 10% drawdown, return to 1% only after making back half of it. This is a drawdown-throttle and it changes the shape of bad periods far more than any entry tweak. The discipline is asymmetrical in practice - traders find it easy to size up after wins and very hard to size down after losses.

See it drawn

Original diagrams for the ideas on this page. Illustrative, not real market data.

Equity curve and drawdown. An account balance plotted month by month. The fall from the $16,000 peak to the $12,000 trough is a 25% drawdown, and the shaded area lasts until the balance climbs back to the old peak.

Working out a position size. Three numbers decide how big a trade is: the account, the share of it put at risk, and the distance from entry to stop. One percent of $25,000 is a $250 budget, and a $0.50 stop divides into that 500 times.