Max drawdown vs daily drawdown: the two rules that end most challenges

Two numbers decide whether you keep the account: the daily loss limit and the maximum drawdown. They are measured differently at almost every firm, and the difference is not cosmetic — the same strategy can be inside one firm's rules and disqualified at another. Since 60-70% of failures are drawdown violations, this is the arithmetic worth doing before the strategy work.

Usually 4-5% of the starting balance, reset at the firm's server midnight. Two traps:

• It often counts open floating loss, not just closed trades. A position sitting −3% can breach the rule without you closing anything.
• The reset time is the firm's, not yours. A position held across their midnight carries its loss into a fresh day — or starts a new day already deep, depending on whether they measure from balance or equity.

This is where firms differ most. Same 10% limit on a $100k account, four meanings:

• Static, from the starting balance. Floor fixed at $90,000 forever. The most forgiving: profits give you room that cannot be taken back.
• Trailing from peak balance. The floor follows your highest closed balance. Win $5k and the floor rises to $95,000.
• Trailing from peak equity. The floor follows your highest unrealised value. A trade that goes +$8k and comes back to breakeven has permanently moved your floor up $8k. This is the strictest and the one that surprises people.
• Trailing until breakeven, then locked. A hybrid: trails while you are below the starting balance plus the limit, then freezes.

Under trailing-equity, a winning trade you did not close makes the account harder to keep. That is not intuitive, and it is why traders who are up money fail anyway.

Take a $100k account, 10% max drawdown ($10,000 of room), and assume you want to survive a run of twenty consecutive losses — which sounds extreme and is not: a gold strategy we run has a longest losing streak of 21 across 818 trades, at a 47.6% win rate. Streaks that long are what a sub-50% win rate means in practice.

The "risk 2% per trade" rule of thumb comes from retail accounts with no hard floor. On a challenge it leaves four or five losses of margin for error against a streak that can run to twenty. The arithmetic, not the opinion, is why challenge risk belongs nearer 0.5% than 2% — and why most people size three to four times too large.

Before paying a challenge fee, run your strategy's history and read three numbers: longest losing streak, maximum drawdown in %, and what closed the losing trades. If max drawdown exceeds the firm's limit anywhere in the history, the strategy cannot pass at that size — it is not a question of luck. Shrink the size until the historical drawdown fits inside the rule with room, and check whether the strategy is still worth trading at that size.

Most are not. That is the honest finding, and it is cheaper to learn here than for a challenge fee.