What is loss aversion?

The tendency for a loss to feel roughly twice as painful as an equivalent gain feels pleasant, which distorts how we weigh risks.

Daniel Kahneman and Amos Tversky, as part of prospect theory in 1979.

How does it lead to bad decisions?

It makes people avoid fair or favourable bets, hold onto losers to dodge “realising” a loss, and be swayed by whether an option is framed as a gain or a loss.

Loss aversion

Also called losses loom larger than gains · Behavioural economics

Loss aversion is the finding that losing something hurts about twice as much as gaining the same thing feels good. Because the pain of a loss outweighs the pleasure of an equal gain, we take irrational risks to avoid losses and pass up fair bets that would pay off.

How it works

We judge outcomes not in absolute terms but as gains and losses from a reference point, and the value curve is steeper on the loss side. So the same £100 registers as a bigger loss than a gain, and framing something as a potential loss reliably shifts choices — even when the odds are identical.

How to use it

Reframing decisions in absolute terms — your final state — rather than gains and losses from today.
Noticing when you’re holding a loser only to avoid “realising” the loss.
Spotting how sellers frame offers as losses avoided (“don’t miss out”) to move you.

Worked example

Most people refuse a coin-flip that pays £150 on heads but costs £100 on tails, even though its expected value is clearly positive. The £100 potential loss simply looms larger than the £150 potential gain — so a good bet feels like a bad one.

Where it fails

It’s context-dependent, not a fixed constant — its size varies with stakes, framing, and person, and some studies find it weaker than the classic “2×.” Treat it as a strong, reliable tilt to watch for, not an exchange rate to plug into a formula.

The deeper point

Its most useful move is to relocate the reference point: because the pain lives in the framing, the same choice turns clear once you ask about your total position rather than what you might “lose” from where you happen to stand. Most bad risk decisions are really bad framings.

Frequently asked

What is loss aversion?: The tendency for a loss to feel roughly twice as painful as an equivalent gain feels pleasant, which distorts how we weigh risks.
Who identified it?: Daniel Kahneman and Amos Tversky, as part of prospect theory in 1979.
How does it lead to bad decisions?: It makes people avoid fair or favourable bets, hold onto losers to dodge “realising” a loss, and be swayed by whether an option is framed as a gain or a loss.

The sunk cost fallacy Expected value Margin of safety Inversion Wikipedia: Loss aversion

The books behind better thinking

Thinking, Fast and Slow — Daniel Kahneman
The Art of Thinking Clearly — Rolf Dobelli
The Great Mental Models, Volume 1 — Shane Parrish
Poor Charlie’s Almanack — Charlie Munger
Super Thinking — Gabriel Weinberg & Lauren McCann
Seeking Wisdom — Peter Bevelin

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Editorial synthesis © ReadGlobe 2026, drawing on the mental-models tradition (Charlie Munger, Farnam Street) and the primary sources for each model. · Last reviewed 2026-07-01.