Psychologie a chování
Loss Aversion: Why Losses Hurt Twice as Much as Gains Feel Good
Key takeaways
- Loss aversion is a proven psychological effect: losses are felt approximately twice as intensely as equally large gains.
- It leads to two opposing mistakes: holding losing positions too long and realising gains too quickly.
- Mental accounting — viewing each position in isolation — amplifies aversion.
- Viewing the portfolio as a whole rather than position by position supports more rational decision-making.
- Scheduled rebalancing according to rules eliminates the need to decide under the emotional pressure of losses.
Loss aversion is a psychological phenomenon in which losses are felt approximately twice as intensely as gains of the same magnitude — and this asymmetric effect underlies a number of the most costly investment decisions.
What the science says
In the 1970s Daniel Kahneman and Amos Tversky demonstrated that people are not rational utility maximisers. They offered test subjects a bet: a 50% chance of winning 150 CZK or a 50% chance of losing 100 CZK. Mathematically positive, yet most refused. Losing 100 CZK was perceived as more painful than the potential gain of 150 CZK was pleasant. Kahneman received the Nobel Prize for this research. For more on his approach to risk, see the article on risk.
How loss aversion harms the investor
It typically manifests in two opposing mistakes:
- Holding losing positions too long: "I'll wait until it gets back to my purchase price." But the market knows nothing about your purchase price. The relevant question is whether the position is attractive today.
- Realising gains too quickly: "Better sell before the profit disappears." The result is a portfolio full of below-average positions and winners sold too soon.
Mental accounting as an amplifier
The brain keeps a separate "account" for each investment — tracking whether it is "in the green" or "in the red". The problem is that a portfolio functions as a whole. A losing position dragging on the whole may have a negative impact even alongside other gains. Switch your perspective to the portfolio's overall performance, not individual positions.
How to tame loss aversion
- Set up automatic rebalancing — rules decide for you.
- Never ask "how much have I gained or lost" — ask "is this position still in line with my plan".
- Accept losses as part of investing — in a diversified portfolio built according to rules, small losses on individual positions are normal.
FAQ
What is loss aversion in simple terms?
A psychological effect in which losses hurt roughly twice as much as an equally large gain feels good. It has been scientifically proven and underlies many flawed investment decisions.
Why is it bad to wait for a losing position to return to the purchase price?
The purchase price is not market information — the market does not care what you paid. The right question is: "Is this position attractive at the current price?" If not, waiting may cost more than realising the loss.
How do I know I am deciding from loss aversion?
If you are hesitating to sell a losing position not because you believe in its future but because you do not want to "confirm" the loss — that is loss aversion. The loss exists in the portfolio whether or not you realise it.