Regret Bias

Regret bias is a behavioral tendency to avoid decisions or actions that could lead to feelings of regret, often causing investors to hold losing positions, avoid switching strategies, or decline promising opportunities out of fear of being wrong.

The emotional logic of regret

Regret is a powerful emotion: the feeling that you should have known better, made a different choice, acted sooner or not at all. Investors with regret bias structure their decisions to minimize the possibility of feeling that way, rather than to maximize expected returns. If a stock falls after you buy it, you feel regret (I should have waited). If you wait and it rises, you feel different regret (I should have bought earlier). To escape both scenarios, you do nothing—but inaction often brings its own regret later. Regret bias is thus a kind of decision paralysis disguised as prudence.

How regret bias keeps investors in losers

A classic manifestation: an investor buys a stock at $50, it falls to $30, and the investor refuses to sell, hoping it bounces back to breakeven. Selling would mean acknowledging the mistake and crystallizing the loss. The investor avoids the immediate sharp pain of saying “I was wrong” and instead endures a slow diffuse pain of watching it decline further. In some cases, the stock does bounce—reinvigorating the decision to hold—but in others, it keeps falling. A more rational approach would ask: is $30 a good price for this stock today, given the new information? If not, sell. But regret bias makes selling feel like admitting failure, so the holder hangs on. This behavior is distinct from sunk-cost fallacy, though they often co-occur.

Inaction bias as the flip side

Regret bias also manifests as inaction bias: the preference for doing nothing because at least inaction cannot be regretted in the same way a bad decision can. If you do nothing and the market falls, you feel some regret (why didn’t I short?), but it is mild; you did not take an affirmative action that went wrong. If you actively shorted and the market rose, the regret is acute: you made a wrong call, visible to yourself and others. This asymmetry pushes people toward passivity. A retiree with cash earning 0% who could earn 3% in Treasury bills avoids the switch because any dip in the bond price would be regrettable (you did something and it went down), while the 0% is invisible regret (nothing to blame yourself for). Regret bias thus can lock in suboptimal outcomes.

The role of reversibility

Decisions that feel reversible are less regrettable. Buying a stock that can be sold at any time feels more reversible than buying a house you cannot easily unload. This is why regret bias sometimes pushes investors toward liquidity; illiquid or long-duration commitments feel more regrettable because the path to reversing them is uncertain. Paradoxically, this can backfire: always keeping the option to reverse a decision leads to perpetual second-guessing and missed benefits of long-term commitment.

Social comparison and regret amplification

Regret is sharpened by social comparison. If your neighbor bought Apple and made 50% while your own picks rose 10%, the regret is magnified beyond the 40% return gap. You did not just earn less; you did worse than someone else with the same information. This drives comparative regret—the fear that if your decision is revealed to be worse than someone else’s, you will feel foolish. Many investors herd into the same popular stocks partly to minimize comparative regret: if everyone bought Tesla and lost money, no one singled out feels as regretful.

Outcome bias and the hindsight trap

Regret bias is often intertwined with outcome bias: judging the quality of a decision by its outcome rather than by the logic at the time the decision was made. A brilliant call that turned out wrong feels regrettable; a lucky guess that turned out right feels vindicated. This distorts learning. An investor makes a poor bet with weak analysis but wins by luck, and they think “I made a great decision.” Next time, they use the same poor analysis, expecting to get lucky again. Regret bias intensifies outcome bias; regrettable outcomes (losses) loom larger, while lucky wins fade into the background.

Strategies to counteract regret bias

One antidote is pre-commitment: decide in advance on a rule or plan (e.g., rebalance quarterly, trim winners at 20% gain, exit losers at -10%) and follow it without second-guessing. Because the decision is made in advance, the emotions of regret have less room to hijack execution. Another is focusing on process, not outcome: ask whether your decision-making process was sound, not whether you got lucky. A third is broad framing: expanding the decision horizon to include all scenarios, making the asymmetry between action and inaction less salient. If you frame regret not as “I will regret if I buy and it falls” but as “I will regret if I miss the long-term opportunity,” the bias shifts.

Regret aversion in portfolio construction

Regret aversion is sometimes used interchangeably with regret bias. Some investors explicitly choose “safe” allocations (e.g., 60/40 stocks and bonds) not because it is optimal, but because everyone else does it; if the allocation fails, at least the failure is shared and socially acceptable. Choosing a more aggressive or unconventional allocation risks being blamed as reckless. This drives a “herd” allocation, not always in investors’ best interests.