Maximum Adverse Excursion: Know Your Worst Moment Before You Trade

Two trades can end in the same place and still be completely different journeys. Imagine buying a stock at $50, watching it slip to $49.10, and then selling it later at $51. Now imagine another trade in the same stock at $50 that barely dips to $49.80, climbs to $52.40, and is also sold at $51. Both earn $1 per share. But one spent much of its life underwater, while the other mostly moved in your favor. Entry and exit prices alone cannot tell those two stories apart. Maximum Adverse Excursion—MAE, for short—can. Think of it as the market’s rear-view mirror: it shows how close the trade came to the edge before it recovered.

What MAE actually measures

MAE is the largest unrealized loss a trade experiences at any point between entry and closing. “Unrealized” means it existed only on paper; you had not sold yet. If you buy at $50, the price falls to $49.10, and the trade later closes at $51, your MAE is 90 cents. That 90 cents happened, even though the final result was green. For a long trade, MAE is the distance from your entry down to the lowest price reached while you were in the trade. For a short trade, it is the distance from your entry up to the highest price reached. If price never goes against you at all, MAE is zero.

The idea was developed in the 1990s by John Sweeney, who later wrote a book on it. His starting point was that, when a trading method is applied consistently, trades that end well usually behave differently early on from trades that end badly—they rarely travel as far in the wrong direction. Once you can measure that pattern, you can decide where protective stops belong, using evidence instead of guesswork.

Why MAE beats a gut-feel stop

A stop-loss is a standing instruction to close a trade if price reaches a level you choose. It is your line in the sand. Many traders pick that line with a rule of thumb: a fixed percentage, a round number, or “how much I can stand to lose.” Those rules are not wrong, but they are not specific to how your own entries behave.

MAE offers a better question to ask your trade history: how far do trades go against me before they finally work, and beyond what point do they keep going against me? To answer it, record MAE for each trade in a journal. Then make a simple scatter plot, with MAE along one axis and final profit or loss on the other. Winning trades appear above the zero line, losing trades below. When you study the cloud of dots, a pattern usually appears: low-MAE trades include many winners, while deep-MAE trades rarely recover. The level where those two groups separate is a natural candidate for a stop.

What the patterns tell you

Three patterns show up again and again. First, if your winning trades barely move against you and your stop is much wider than their MAE, your stop may be too wide. It is providing protection you are not really using. Tightening it in steps could reduce the size of losses without costing many winners. The goal is a stop that lets most good trades live while cutting off trades that suffer large losses.

Second, if winners routinely wander close to your stop before turning around, the opposite may be true: your stop may be too tight. It could be sitting inside ordinary market noise, creating false exits. Widening it—while reducing position size so the dollar risk stays the same—can give trades enough room to develop. The data, not fear of missing out, should tell you which case you are in.

Third, watch for winning trades with deep MAE. A trade that goes $1,000 against you and finally closes $100 higher is not a sign of skill; it is a sign of a risky process. It worked that time, but on a day when the recovery never comes, that trade becomes a serious loss. Deep-MAE winners are worth studying closely, because they often reveal late entries or overlarge positions.

The mirror image: maximum favorable excursion

MAE is only half of the story. Maximum Favorable Excursion, or MFE, measures the furthest a trade moved in your favor while it was open. If a trade peaked at $3.20 in profit and you closed it at $2.00, you captured 62.5 percent of the available move. That gap is where exits quietly leak away. A strategy that consistently captures less than half of its favorable moves is probably exiting too early. For many strategies, capturing roughly two-thirds or more of the available move is a healthy target, though the right number depends on style and timeframe.

MFE also helps spot trades that were winners and then turned into losers. If many losing trades once showed a large favorable excursion before reversing, the problem may not be the entry. It may be holding too long instead of taking profits. Read together, MAE and MFE describe the whole journey of a trade: how much heat it absorbed and how much opportunity it offered.

What the data requires

There is a catch: MAE cannot be calculated from entry and exit prices alone. For longs, you need the lowest price reached during the trade; for shorts, the highest price reached. Many brokers do not include those extremes in standard trade exports, and a spreadsheet created after the fact cannot recover them. This is why journals that connect directly to a broker or platform are useful—they capture the information automatically. If you journal by hand, note the worst and best prices before closing each trade.

One or two trades tell you almost nothing. Most practical guidance suggests collecting at least 30 or 40 trades per setup before reading patterns, and closer to 60 or 100 for reasonable confidence. Then change one variable at a time. If you tighten the stop and widen the target in the same week, you will never know which change helped. After a month or two of new data, re-measure and see whether the pattern improved.

The honest limitations

MAE is a risk-management lens, not a crystal ball. It describes what your trades have done, not what the next trade will do. There is no universal MAE number that is right for everyone; a quick scalp and a slow swing trade will have very different profiles. Position size also matters: the same price movement means different dollar amounts for different traders, and if you scale in and out, the actual account experience can differ from a full-position calculation. Treat MAE as one piece of evidence, not a guarantee.

Still, the habit is powerful. It turns a vague motto like “keep your losses small” into a measurable, reviewable number. It gives you a way to look back at any trade and ask: how bad did this one get, and was that worth it? In a world where a profitable trade can hide a scary amount of risk, that is a question worth asking every time.