Trailing drawdown vs static drawdown: the rule that kills EAs

Two prop firms advertise "10% maximum drawdown". Same number, same headline. The trader who passes Firm A is wiped out at Firm B with the same trades. The difference is trailing vs static drawdown — and it is the most consequential single rule in the prop-firm world.

The two floors

Both rules define a floor — an equity level you cannot touch without breaching. The difference is how the floor moves.

• Static drawdown. Floor = starting balance − X%. It never moves. If your account starts at $100,000 and the rule is 10%, your floor is $90,000 forever, regardless of how much profit you make.
• Trailing drawdown. Floor = peak equity − X%. The floor moves up as your equity makes new highs, and never moves down. Your earnings are eaten by the floor as you go.

A worked example

Take a $100,000 prop account with a 10% maximum drawdown rule. You trade well for two weeks and bring the account to $108,000. Then you give back $5,000 to $103,000. Are you OK?

Now you give back another $5,000 to $98,000. Are you OK?

Same account. Same trades. One trader is fine; one trader is fired. The trailing rule turned a 5% pullback from peak into a structural risk that the static rule absorbs without flinching.

Why trailing is brutal

The trailing floor eats your profits. Every dollar you make tightens the floor by one dollar. Drawing back from a peak does not just give back the gain — it pushes you toward the floor that your gains created. A strategy with a 5% drawdown profile and a 10% trailing rule has only a 5% safety margin from any peak, no matter how much you make in absolute terms.

Strategy implications

The rule type changes what kind of strategy makes sense on the account.

Momentum / trend-following → favours static

Trend strategies bank large profits on a few big runs, then give back during chop. The give-back is structurally larger in absolute terms because the wins are larger. A static rule absorbs the give-back as long as it stays inside the original X% buffer. A trailing rule re-tightens the buffer at every new equity high, so a normal post-trend consolidation can breach.

Mean-reversion → tolerable on both, leans trailing

Mean-reversion strategies tend to have shallow drawdowns and many small wins. The equity curve is smoother. Trailing rules eat at the curve too — but the absolute give-back per peak is small, so the trailing eats less per high. Mean-reversion strategies often pass trailing accounts that trend strategies cannot.

Martingale / averaging → toxic on both, lethal on trailing

Strategies that average into losers produce sudden equity spikes (when the position recovers) and sudden equity craters (when it does not). On a trailing rule, the post-recovery high resets the floor close to current equity — meaning the next loss instantly breaches. We have never seen an undisclosed-martingale system survive a trailing DD account.

How to read the fine print

Firms describe the same rule with different language. Common phrasings and what they actually mean:

Sizing for trailing

A practical rule: on a trailing-DD account, size so your per-trade drawdown contribution is at most 1/5 of the rule. If the firm allows 10% trailing DD, your worst single-trade scenario should be ≤2% of equity. With a 0.5% risk-per-trade rule, your strategy survives a four-loss streak before approaching breach territory — assuming no open-position drawdown stacks on top.

When trailing is actually fine

Trailing DD is not inherently bad. For traders running shallow-drawdown strategies on small accounts where the per-trade absolute risk is small, the trailing floor barely matters — you would never come within striking distance of it on a normal week. The rule only bites traders whose strategy produces equity-spike-then-reversion shapes.

Pair the rule with the strategy. The same prop account is excellent for one style and brutal for another.

The bottom line

Static drawdown lets your profits permanently expand your buffer. Trailing drawdown locks the buffer at peak. The same "10% max DD" headline can mean either, and the gap between the two is the difference between a profitable funded year and a wiped account by month two. Read the formula before you read the fee.