The Disposition to Sell Winners Too Early and Ride Losers Too Long: Theory and Evidence
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What they found
Shefrin and Statman named and explained the disposition effect. Combining prospect theory (people are risk-seeking in losses), mental accounting (each position is its own account with its own reference point), regret aversion (selling a loser makes the mistake official), and self-control problems, they explained why investors sell winners readily and hold losers stubbornly. They presented early evidence from mutual fund flows and from the timing of realized gains and losses, including the tendency for losses to be realized only in December for tax reasons.
What you can use
- The urge to hold a loser 'until it comes back' and to lock in a small gain quickly has a name and a psychological mechanism.
- Each position becomes its own mental account anchored at the entry price, which is why closing a loser feels like admitting a mistake.
- The rational behavior is the opposite: tax rules favor realizing losses, and momentum favors holding winners.
Caveats
The empirical section is limited by 1980s data; Odean (1998) provided the definitive test. Theory paper with multiple overlapping explanations.
Tags: behavioral, disposition-effect, mental-accounting, loss-aversion
Summaries are our own reading of the paper, not the authors' words. Educational only, not advice. Discuss it in Book Club.