Why does a loss hurt more than the same-sized gain feels good?
You have learned to build a portfolio, allocate it and measure it. This course is about the thing that quietly undoes all three: the person operating the portfolio. We start with the best-documented asymmetry in the whole field.
The asymmetry
Losing €1,000 does not feel like the mirror image of gaining €1,000. Repeated experiments put the pain of a loss at roughly twice the pleasure of an equal gain. That single number — call it a factor of about two — explains a startling amount of investor behaviour.
Because a loss on paper still feels provisional, but a realised loss feels final, we get a predictable pattern: sell the winners, keep the losers. Selling a winner converts a paper gain into a certified success. Selling a loser converts a paper loss into an admitted mistake. So the account slowly fills with the positions the investor is least willing to look at. That pattern has a name — the disposition effect — and it shows up in brokerage records across countries, decades and asset classes.
What it costs
Two positions, €10,000 each, both bought at 100.
- Position A rises to 130 → €13,000. It feels good to "take profit," so it is sold.
- Position B falls to 70 → €7,000. It is held, because "it will come back" and selling would make the loss real.
A year later, A has risen a further 20% and B has fallen a further 25%.
- The sold winner would have been worth about €15,600 — €2,600 left behind.
- The kept loser is worth about €5,250 — a further €1,750 gone.
Total damage: about €4,350 on €20,000 committed, roughly 22% — and not one euro of it came from a bad analysis. It came from which position was allowed to be sold.
This is an illustration of the pattern, not a claim that winners always keep winning. The point is narrower and harder: the decision was driven by the purchase price, and the purchase price is not information. The market has never seen it, does not know it, and will not respect it.
The reframe that helps
A holding is a decision you are re-making every single day. The honest question is never "am I up or down on this?" It is: "knowing what I know now, with this money free, would I buy this today at this price?" If the answer is no, the position is being held by your feelings about the entry price rather than by your view of the asset.
Professionals institutionalise that reframe. They mark positions to market and evaluate the portfolio they hold now against the portfolio they would choose now — a comparison in which entry prices simply do not appear.
Try it now
- Open your holdings and sort them by unrealised profit and loss. For the three biggest losers, answer honestly: would you buy each one today, at today's price, with fresh money?
- Look back at your last five sales. How many were winners, and how long had you held each? Compare with how long you have held your current losers — that ratio is your personal disposition effect.
- Now rehearse the thing you cannot see in your own record. On the chart below, pick any point where a holder would plausibly have sold "to lock in a profit", and Measure forward from it. Do it three times, at three different points. Some of your measurements will be a relief and some will not — which is the honest answer, and the reason to collect evidence about a process rather than score yourself on one exit.