There is a large body of academic evidence demonstrating that individual investors are subject to the “disposition effect.” Those suffering from this phenomenon, which was initially described by Hersh Shefrin and Meir Statman in their 1985 paper, “The Disposition to Sell Winners Too Early and Ride Losers Too Long: Theory and Evidence,” tend to sell winning investments prematurely to lock in gains and hold on to losing investments too long in the hope of breaking even.
As Toby Moskowitz more recently explained in his AQR working paper, “Explanations for the Momentum Premium,” the disposition effect “creates an artificial headwind: when good news is announced, the price of an asset does not immediately rise to its value due to premature selling or lack of buying. Similarly, when bad news is announced, the price falls less because investors are reluctant to sell.” The disposition effect therefore creates predictability in stock returns (momentum).
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