Reading results 3: drawdown and the equity curve
Two strategies can end at the same profit and be nothing alike to hold. Learn to read the equity curve and maximum drawdown, and what survivability really means.
Part of the Backtesting and Research track on Agenticks. About 10 minutes, written for a advanced reader.
Win rate told you how often a rule wins. Expectancy told you the average result per trade. Both are summary numbers. They flatten the whole test into a single figure and hide one thing that matters just as much: the order the wins and losses arrived in. That order is what the equity curve shows. It is the line that traces your account balance trade by trade, from the first trade to the last. A strategy can have a healthy expectancy and still drag you through a stretch so ugly that no real person would have stayed in it. Reading the curve, and the deepest hole it digs, is how you find that out before it finds you.
The equity curve is the shape of the ride
Two strategies can end at the exact same profit. One climbs steadily; the other doubles, crashes, and grinds back. Same ending, completely different experience. The final number tells you where you arrived. The equity curve tells you what you had to live through to get there.
Look at any equity curve and you will see it make new highs, then dip, then recover, then make new highs again. A drawdown is one of those dips: a drop measured from the most recent peak down to the low that follows it, before a new peak is set. While you are below the old peak, you are, in trading slang, underwater. Maximum drawdown is the single deepest of all those dips across the whole test, usually quoted as a percentage of the balance at the peak. If your account ran to ten thousand dollars and then fell to seven thousand before recovering, that is a thirty percent maximum drawdown. It does not matter that the account later went on to new highs. The maximum drawdown records the worst moment, because the worst moment is the one that tests whether you can actually hold the strategy.
Profit you cannot hold is not real profit
Survivability is whether you could stay in a strategy through its worst stretch without breaking a risk limit or quitting in disgust. A backtest that ends green but dips fifty percent in the middle is only profitable on paper, because almost nobody sits through losing half their account to collect the recovery.
This is the part that separates a number on a screen from a strategy a human can actually run. Picture two backtests that both finish up forty percent over the same period. The first never falls more than eight percent below a prior peak. The curve wobbles but climbs. The second, on the way to the same forty percent, drops forty-five percent at one point. For months the account is deep underwater. On a results summary, both show plus forty percent. But the second one is almost certainly untradeable in real life. Long before the recovery, you would have hit a risk limit, panicked out, or simply stopped trusting the rule. Maximum drawdown is the number that exposes this. It is the pain threshold of the strategy, and if the pain is more than you can take, the final profit is irrelevant because you were never going to reach it. There is a second cost hidden in deep drawdowns: the climb back is steeper than the fall. A drawdown of fifty percent does not need a fifty percent gain to recover. It needs a one hundred percent gain, because you are now growing from a much smaller base. That asymmetry is why traders watch drawdown so closely. Small drawdowns are an annoyance; deep ones are a trap that can take years to dig out of.
An account falls 50% in a drawdown. What gain on the reduced balance is needed just to get back to the old peak? 100% Correct. Falling 50% halves the balance, so you must double what is left, a 100% gain, just to break even. Deep drawdowns are punishing precisely because recovery is asymmetric.
- Equity curve
- The shape of the ride, trade by trade
- Maximum drawdown
- The worst peak-to-trough drop you would have sat through
- Survivability
- Whether you could realistically hold it through the worst part
- Final profit
- Where you arrived, not what you endured to get there
One more honest point. A single backtest gives you one equity curve: one particular order of wins and losses that happened in the past. Reorder those same trades and the curve, and the maximum drawdown, would look different. That is variance at work, and it is why a deep drawdown in a backtest is a floor, not a ceiling. The live version could easily be worse. This is also why sample size matters here. A drawdown read off ten trades tells you almost nothing, because luck dominates a small sample. A drawdown read off several hundred trades is a far more honest estimate of how deep the strategy can go. When you read a results screen, you are really asking two questions at once: how deep did it fall, and were there enough trades for that number to mean anything.
Put these in the order you should read a backtest's risk, from first sanity check to final judgment.
- Check the trade count is large enough to trust
- Read the maximum drawdown as a percentage
- Look at the equity curve's shape, not just its endpoint
- Decide whether you could survive the worst stretch
equity drawdown survive
So when a backtest hands you a green final number, do not stop there. Ask the curve two questions: how deep did it ever fall below a prior high, and would you have stayed in long enough to reach the end. If the deepest drawdown is more than you could stomach, the profit on the screen is a number you were never going to collect. Profit is the destination. Drawdown is the road. A strategy is only worth running if you can survive the road.
You can now read a strategy's survivability
You know how to read the equity curve and maximum drawdown, why recovery is asymmetric, and why a profit you cannot hold through the worst stretch is not real profit.
Common questions
- What is drawdown in a backtest?
- Drawdown is a drop from a previous peak in the account balance. Maximum drawdown is the deepest of those drops over the whole test, usually shown as a percentage. It measures the worst losing stretch the strategy put you through.
- Why does the equity curve matter if I already know the final profit?
- Because two strategies can finish at the exact same profit while one rose smoothly and the other plunged in the middle. The shape of the ride decides whether a real person could hold the strategy long enough to reach that ending.
- What does survivability mean for a trading strategy?
- Survivability is whether you could realistically stay in the strategy through its worst stretch without blowing past a risk limit or quitting. A profitable strategy with a drawdown too deep to stomach is not survivable in practice, so its profit is theoretical.
Terms defined in this lesson
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