What this lesson is about
The single most replicated finding in behavioral economics. And the quiet force behind an enormous share of bad investing decisions.
Part 1 of 2
If you found $100 on the sidewalk, you'd feel great. But if you lost $100 from your wallet, you'd feel a lot worse. That difference isn't just a quirk; it's a key finding in behavioral economics. Psychologists Daniel Kahneman and Amos Tversky studied "prospect theory" and discovered that losses hit you about twice as hard as gains feel good. Losing $100 feels like losing $200, not just $100. This idea, known as loss aversion, affects many financial decisions, often without you even realizing it.
In investing, loss aversion shows up all the time. It’s why selling a losing stock feels so much tougher than buying one. Investors often cling to a failing investment longer than they should. Why? Because selling would "make the loss real." A portfolio's paper losses during a market dip can trigger panic selling, locking in losses that a calmer perspective might have avoided.
Quick check
What does "loss aversion" describe?
Loss aversion is specifically about the asymmetry in how losses and gains feel psychologically, not about avoiding risk altogether or any tax mechanic.
Part 2 of 2
Quick check
Research by psychologists Daniel Kahneman and Amos Tversky (part of "prospect theory") suggested losses are felt roughly how many times as intensely as equivalent gains?
Roughly a 2-to-1 ratio is the commonly cited finding from the original research and subsequent replications, though the exact ratio varies somewhat by study and context.
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