Drawdown limits and how prop firm rules work
A trailing drawdown measured on unrealized profit behaves very differently from one measured on closed balance. Traders find out which they have at the worst moment.
Drawdown is the decline from a peak in account value to a later trough. It is the standard measure of how bad things got, and it is the number most funded-account programmes are built around.
Why it is measured from the peak
Because recovery is not symmetric with loss. A fall requires a proportionally larger gain to get back, and the gap widens the deeper the fall. Measuring from the high-water mark captures the size of the hole rather than just the net change.
The common rule types
Maximum daily loss. A limit on losses within one trading day, usually resetting overnight. Breaching it typically ends the day or the account.
Maximum overall drawdown. A floor on account value. Two very different forms exist:
| Static | Trailing |
|---|---|
| Floor is fixed at the start | Floor rises as the account makes new highs |
| Profits create permanent room | Room stays constant, moving up behind you |
Profit target. An amount to reach before the account converts or pays out.
Consistency rules. Limits on how much of total profit may come from a single day, intended to exclude accounts that got there on one outlier.
The detail that catches people. Some trailing drawdowns track the highest unrealized account value, not the closed balance. If a position goes far in your favour and then comes back, the floor has already ratcheted up to that peak — and the account can breach on a trade that closed at a profit.
Whether the high-water mark uses realized or unrealized value is the single most important line in the rules, and it is frequently buried. Find it before you fund anything.
What these rules do to behaviour
A hard floor changes the calculation in ways worth being explicit about. Position sizes that would be reasonable on an unconstrained account can be too large when a fixed floor sits close below. The distance to the floor is a constraint on sizing, and it tightens after every loss.
It also creates a real tension. Reaching a profit target rewards taking risk; the drawdown limit punishes it. The two pull opposite ways, and the resolution is arithmetic done in advance rather than judgement applied in the moment.
Reading a rule set
- Is the drawdown static or trailing?
- If trailing, does it track realized or unrealized equity?
- Does the daily loss limit reset, and at what time in which timezone?
- Are limits checked continuously or at the close?
- What happens on a breach — the day, or the account?
These are answerable from the documentation before you commit money, and each one changes what sizing is sensible.