A maximum drawdown limit is a predefined loss threshold that triggers mandatory action — reducing size, stopping trading, or reviewing strategy. Common limits: daily max loss (e.g., 3%), weekly max loss (e.g., 5%), monthly max loss (e.g., 10%), and total max drawdown (e.g., 20%). Professional trading firms and prop firms enforce strict drawdown rules.
Daily loss limit: stop trading for the day if reached. Weekly loss limit: reduce size or stop for the week. Monthly loss limit: mandatory strategy review. Total account drawdown: maximum acceptable peak-to-trough decline. Trailing drawdown (prop firms): drawdown measured from highest equity point. Revenge trading prevention.
Set limits before you start trading — they must be predetermined. Hit your daily limit? Close all positions and walk away. No exceptions. Hit your weekly limit? Reduce position sizes by 50% for the remaining week.
Daily limit hit: close all positions, stop trading. Weekly limit: reduce size or stop. Monthly limit: full strategy review, potential pause. Total drawdown limit: stop trading, review everything, seek mentorship or change approach.
Applies to all trading activity
Drawdown limits are not optional — they are the safety net that prevents catastrophic loss. The discipline to respect drawdown limits is arguably more important than any entry strategy. Prop firms fail traders for drawdown violations even when the trader eventually would have recovered.
The Kelly Criterion is a mathematical formula for determining the optimal bet size to maximise long-term growth rate. Kelly = (bp - q) / b, where b = odds received, p = probability of winning, q = probability of losing. While theoretically optimal, full Kelly is too aggressive for most traders — half-Kelly or quarter-Kelly is more practical.
Risk of ruin calculates the probability that a trader will lose a specified percentage of their account — typically enough to end their trading career — given their win rate, average reward-to-risk ratio, and percentage risked per trade. This mathematical framework quantifies whether a trading strategy is survivable over the long run and helps traders set appropriate risk limits to ensure longevity.
Trailing stop strategies dynamically adjust your stop-loss level as a trade moves in your favour, locking in progressively more profit while still giving the trade room to develop. Unlike fixed stops, trailing stops adapt to market volatility and price action, allowing traders to capture the majority of a trend move without exiting prematurely on normal pullbacks.
The Sharpe ratio measures risk-adjusted return by dividing excess return (above the risk-free rate) by the standard deviation of returns. The Sortino ratio improves on Sharpe by penalising only downside deviation, recognising that upside volatility is desirable. Both ratios help traders compare strategies on a level playing field and identify which approaches deliver the best returns for their level of risk.