Drawdown Episodes

What are Drawdown Episodes?

A drawdown is the percentage decline from a prior high in a strategy's value. As an equity curve rises and falls, it sets a series of new peaks; every time it slips below the most recent peak it is in drawdown, and it stays in drawdown until it claws back to that high and sets a new one. A drawdown episode is one complete cycle of that process: a peak, a slide down to a trough, and the recovery back to the prior peak. The backtest's history is a sequence of these episodes strung end to end, separated by the moments when the strategy is at a fresh all-time high.

Each episode is described by a few facts. The depth is how far the value fell from peak to trough, expressed as a percentage. The peak date and trough date mark when the decline began and where it bottomed. The recovery date, when it exists, marks when the strategy regained the old high; the span from peak to recovery is the underwater period, the full length of time an investor would have spent below where they started. Some episodes never recover within the test window, in which case they are still open at the end and have a depth and a trough but no recovery date yet.

SledgeKey surfaces the most significant of these episodes as a ranked list, typically the deepest several, so you can see not just the worst decline but the shape of the whole risk history. Maximum drawdown is simply the depth of the single worst episode on that list. The list adds the context that a single number cannot: how many serious declines there were, how deep the runners-up went, and crucially how long each one took to heal.

Formula

The drawdown at any point is the gap between the current value and the running peak, divided by that peak, so it is always zero or negative. When the value sets a new high the running peak updates and the drawdown resets to zero, which marks the boundary between one episode and the next. Within an episode, the depth is the most negative drawdown reached, that is the value at the trough relative to the peak: Depth = (V at trough minus V at peak) divided by V at peak. The recovery time is the number of periods from the peak until the value first equals or exceeds that peak again, and the time to trough is the number of periods from the peak down to the low point.

SledgeKey computes these from the strategy's value series over the test window, using the running-maximum definition above so that depth is always measured against the prior high rather than against the starting value. Depths are reported as percentages and durations as elapsed time, and the episodes are ranked so the deepest declines sit at the top. Because the calculation references the running peak rather than a fixed starting point, a strategy that has doubled and then falls 20% from that doubled level shows a 20% drawdown, not a gain; the metric always measures pain relative to the best the strategy had achieved at that moment.

Why Drawdown Episodes Matter in Backtesting

Drawdown episodes inform the question that decides whether a strategy is actually livable: not just how bad the worst loss was, but how often serious losses happened and how long you would have had to wait, underwater, for each to heal. Two strategies can share an identical maximum drawdown of 30% and feel completely different to hold. One reached that 30% in a single sharp crash and recovered in six months; the other ground down to 30% over two years and took four more to recover. The single max-drawdown number cannot tell them apart, but the episode list shows the recovery times side by side and makes the difference obvious.

The decision this informs most directly is whether you could realistically stay invested. The behavioral failure of most strategies is not that they lose money on paper but that the holder abandons them during a long underwater stretch, locking in the loss right before the recovery. A backtest that shows several multi-year underwater periods is warning you that the strategy demands patience few investors actually have. Recovery time is the dimension of risk that the headline metrics quietly omit, and it is often the one that determines whether a strategy survives contact with a real human's nerves.

The episode list also exposes whether the worst case was a fluke or a pattern. If the deepest drawdown is far worse than the second and third, the strategy's risk may be concentrated in one rare event whose true probability is hard to judge from a single occurrence. If the top several episodes are all similar in depth, the strategy reliably produces declines of that size, which is easier to plan around. Reading the spread of the episodes is how you tell a one-off scar from a recurring habit, a distinction that maximum drawdown alone hides.

How SledgeKey Implements Drawdown Episodes

Drawdown episodes appear on the backtest results page as a ranked list of the strategy's largest declines, computed from the same value series that drives the equity curve. Each entry shows the depth of the decline as a percentage, the dates the episode spanned, and the recovery duration, with the deepest episode at the top. That top entry is the maximum drawdown reported elsewhere in the results, so the list places the single worst number in the context of the declines that came near it.

An episode that has not yet recovered by the end of the test window is shown as still open, with a depth and a trough but no recovery date, which is the honest reading: the strategy had not regained its prior high by the time the data ran out. Because the depths are measured against the running peak rather than the starting capital, an episode late in a long winning run can still register as a deep drawdown even while the strategy remains far above where it began. Read the list together with the equity curve, where each episode is the visual dip below the prior high, and with maximum drawdown, which is just the depth of the worst line item here.

Common Pitfalls

The first pitfall is fixating on depth and ignoring recovery time. A 25% drawdown that recovers in four months is a far gentler experience than a 20% drawdown that stays underwater for three years, yet the shallower-but-longer episode is the one more likely to break an investor's resolve. Depth measures how far you fell; recovery time measures how long you had to live with it, and for most people the second number is the one that actually determines whether they stay the course. Read both columns, not just the percentage.

The second pitfall is treating an open, unrecovered episode as if it were resolved. When the worst drawdown is still in progress at the end of the backtest, its recovery time is unknown, not zero. A strategy that ends the test window deep underwater has not proven it can recover at all; it has only proven it can fall. Counting that open episode's recovery as instantaneous, or quietly ignoring it, flatters the strategy precisely where it is weakest.

The third pitfall is forgetting that drawdowns are measured against the running peak, not the starting value or the average. A strategy can be up 150% over the test and still show a punishing 35% drawdown episode, because the decline is measured from the high it had reached, not from where it began. This is the correct convention, since it captures the loss an investor who bought at that peak would have felt, but it surprises people who expect drawdown to be relative to their entry. The episode list describes the pain of the worst-timed entry into each decline, which is exactly the risk worth respecting.

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