You make a few points on the DAX and cash out immediately, relieved. An hour later, another position moves against you. You let it run, telling yourself it will come back. This reflex has a name: the disposition effect. It is one of the best-documented biases in behavioral finance—and one of the costliest for an active trader.
A bias identified forty years ago
Economists Hersh Shefrin and Meir Statman coined the term in an article in the Journal of Finance with a self-explanatory title: selling winners too early and holding losers too long. They explain it through three mechanisms, as BehavioralEconomics.com’s encyclopedia points out: loss aversion, regret avoidance, and mental accounting.
The first comes from Daniel Kahneman and Amos Tversky’s prospect theory, published in 1979 in Econometrica. Its best-known principle can be summed up in one sentence: losses loom larger than gains. In their 1992 version, the two researchers added diminishing sensitivity: the farther you move from your reference point, the less each additional euro is felt.
Apply that to your screen. When you are in profit, you become cautious: a certain gain feels better than a larger but uncertain one. You take the money. When you are losing, you become a gambler: faced with a certain loss or a bet that could erase it, you take the bet. You hold on.
Regret makes things worse. As long as the position remains open, the loss is still “unrealized.” Closing it means admitting the mistake. Mental accounting does the rest: each trade becomes a separate little account that you refuse to close in the red. But only the overall balance matters.
What real accounts show
The bias is not confined to the laboratory. In 1998, Terrance Odean analyzed account statements from a large US discount broker. His method was straightforward. On each day when investors sold, he counted the unrealized gains and losses in their portfolios, then looked at which ones they realized.
The result, as shown in his study: faced with an unrealized gain, investors sell significantly more often than when faced with an unrealized loss. Odean rules out rational explanations. Neither portfolio rebalancing nor fees justify the behavior, and the subsequent performance of the securities investors kept does not vindicate them.
The same gap appears elsewhere. Among Taiwanese retail investors, a study published in the Pacific-Basin Finance Journal also found a higher proportion of realized gains than realized losses.
A more recent study is especially relevant to today’s trader. Rawley Heimer tracked retail traders before and after they joined a social trading platform. His conclusion, published in the Review of Financial Studies: access to the network nearly doubles the size of the disposition effect. Displaying your positions to your peers makes losses even harder to accept. Think about that the next time you post an open trade in a Telegram group or Discord server.
A bias that hides in plain sight
For a forex or index trader, the disposition effect rarely looks like holding a stock for years. It slips into small, seemingly harmless actions:
- widening the stop “just a little” because the next level seems more logical;
- averaging down on a losing position, rebranded as “adding to the trade”;
- manually exiting at the first contrary candle, well before the planned target;
- moving the stop to breakeven too early, out of fear that a gain will turn into a loss;
- turning an intraday trade into a “core position” because it is in the red at the end of the day.
The outcome is mechanical. Your gains stay small while your losses grow. You can be right more than half the time and still lose money.
For a prop firm candidate, the danger is doubled. A single loss you allow to run can breach the daily loss limit and end the challenge in one session.
The broader context is hardly encouraging. Between 2009 and 2012, a large share of the retail clients studied by the AMF lost money trading forex and CFDs. This figure does not measure the disposition effect. But an asymmetry between small gains and large losses is enough to sink an account, even with a good read on the market.
Your journal sees it before you do
Trade by trade, the bias remains invisible: each decision, taken in isolation, has its justification. It only appears over a series of trades, and that is precisely what your journal is for. If you are starting from scratch, the trading journal guide details which fields to complete. To track this bias, five measures are enough:
- Average gain and average loss, expressed in R (R is the trade’s initial risk). An average loss greater than 1 R points to stops being moved.
- Average holding time for winners and losers. Losers held much longer than winners are a clear sign of the bias.
- The share of trades where the stop moved against you. Create a dedicated tag and apply it honestly.
- Realized R compared with the planned R at entry, for winning trades.
- Maximum favorable excursion: how far price moved in your favor before you exited.
This is a classic trap. A trader affected by the disposition effect often boasts an impressive win rate, paying for it with the size of their losses. Correcting the bias almost always lowers that rate. That is good news.
The market does not know the price at which you entered. Your entry price matters only to you.
Five rules to break the habit
Set your stop and target at entry, using live orders. Not in your head: on the platform. An order that is already placed saves you from making a decision under emotional pressure. The corollary: the stop may move only in the direction of the trade, never against it.
Take the blank-page test. When facing a losing position, ask yourself: “If I were flat, would I open this trade now, at this price?” If the answer is no, there is no reason to keep it. This test removes the reference point—your entry price, the true driver of the bias.
Write your exit plan before entering. Partial exit at a given level, trailing stop below a given swing low, full exit on a given signal. Any early exit not included in the plan should be recorded in the journal as a mistake, even if it made money.
Hide the euro result during the session. Display your positions in points or R if your platform allows it. The fewer red or green numbers you see, the less relief and pain will drive your clicks. And keep your open trades to yourself: Heimer’s study shows the cost of other people’s scrutiny.
Review your trades every week, sorted by duration. Compare the five trades held the longest with the five held the shortest. The bias often becomes obvious. An automated journal such as Edgyx calculates these duration and R gaps for you, and its Ora coach can flag drifting stops before they become a habit.
Key takeaways
- The disposition effect means cutting winners too early and letting losers run. It is driven by loss aversion, regret avoidance, and mental accounting.
- In real accounts, Odean measured a higher proportion of realized gains than realized losses.
- According to Heimer, exposing your positions on a social network nearly doubles the bias.
- Your journal makes it visible: average losses above 1 R, losers held longer than winners, and stops moved.
- The remedies are mechanical: place orders at entry, never move the stop farther away, write the exit plan in advance, and use the blank-page test.
- A lower win rate after correcting the bias is not a failure if expectancy turns positive.
