Loss Aversion Bias: Why Losing $100 Hurts More Than Gaining $200 Feels Good

We are now entering Part 4 of Michael Pompian’s book, and this is where things get really interesting. We are moving from cognitive biases (errors in thinking) to emotional biases. And the first one is a big one.

Here’s the thing about loss aversion: it is probably the single most damaging bias an investor can have. Not because it is rare. Actually, the opposite. Almost everyone has it. It is so common that researchers gave the most visible symptom a medical-sounding name: get-even-itis.

Yes, that is a real term used by investment professionals.

What Is Loss Aversion?

Loss aversion was first described by Daniel Kahneman and Amos Tversky back in 1979 as part of their prospect theory work. The basic idea is simple: losing money hurts about twice as much as gaining the same amount feels good.

Think about it. If someone offers you a coin flip where you can win $100 or lose $100, most people will say no. The pain of potentially losing $100 is just too strong, even though the odds are perfectly fair. You would need the potential win to be around $200 before you would take that bet.

This is not rational. Mathematically, a fair bet is a fair bet. But emotionally, we are wired to avoid losses much more aggressively than we chase gains.

The Two Ways It Destroys Your Portfolio

Pompian explains that loss aversion hits investors from both directions. And the combination is brutal.

First: you hold losers too long. This is the get-even-itis part. You bought a stock at $50, it dropped to $30, and now you are sitting there thinking “I will sell when it gets back to $50.” Meanwhile, the company might be in serious trouble. The fundamentals might be terrible. But you cannot bring yourself to sell because selling would make the loss “real.”

Some investors even say “it is only a paper loss.” And technically, yes, until you sell, you have not realized the loss for tax purposes. But here is the problem: if you went to sell that stock right now, you would get $30. That is a very real loss. The fact that you have not pressed the sell button does not change the reality of your situation.

Second: you sell winners too early. When a stock goes up, loss-averse investors get nervous. They think “I better lock in this profit before it disappears.” So they sell. But often, the stock was going up for good reasons. The company was doing well. By selling too early, they cut off the upside potential.

So you end up with a portfolio full of losers (because you will not sell them) and you keep getting rid of your winners (because you cannot resist taking profits). The result? Your portfolio returns suffer badly.

The Disposition Effect

Researchers Hersh Shefrin and Meir Statman gave this pattern a name: the disposition effect. It is the tendency to sell winners too quickly (risk-avoidance behavior) and hold losers too long (risk-seeking behavior).

Notice something weird here? When you are losing money, you suddenly become a risk-taker. You hold onto that sinking stock, hoping it will come back. But when you are making money, you become risk-averse. You want to lock in that gain immediately.

This is exactly backwards from what you want. You should be taking risks to increase gains, not to avoid admitting losses.

The Equity Premium Puzzle

Pompian discusses a fascinating piece of research by Shlomo Benartzi and Richard Thaler that connects loss aversion to something called the “equity premium puzzle.”

Here is the puzzle: historically, stocks have returned about 5-6% more per year than safe Treasury bills. Over decades, that is a massive difference. So why does not everyone just buy stocks?

Benartzi and Thaler came up with the concept of “myopic loss aversion.” The idea is that investors who check their portfolios frequently are more likely to see short-term losses. And because losses hurt twice as much as gains feel good, frequent portfolio checking makes stocks look much less attractive than they actually are.

Their research showed that the behavior makes sense if investors are evaluating their portfolios about once a year. At that frequency, stocks show losses often enough to trigger loss aversion. But if you only check every 5 or 10 years, stocks almost always show gains, and loss aversion does not kick in.

The practical lesson? Stop checking your portfolio so often. The more you look at it, the worse your decisions will be.

What You Can Do About It

Pompian offers some practical advice for fighting loss aversion:

Use stop-loss rules. Before you buy any investment, decide at what point you will sell if it drops. Maybe 10%, maybe 15%. The key is to set this rule before emotions get involved. Just make sure your stop-loss is wide enough to account for normal volatility. You do not want to sell just because the stock had a normal bad day.

Use price-appreciation rules too. Just like you set rules for when to sell losers, set rules for when to sell winners. Base these on fundamentals and valuation, not on fear. The goal is to let your gains run. And in taxable accounts, remember that you want to delay paying taxes on gains as long as possible.

Educate yourself about risk. If you are holding onto a losing stock because you cannot face the loss, take a hard look at the company’s actual risk profile. What is the standard deviation? What do analysts say? If the investment is objectively bad, selling it is not admitting failure. It is being smart.

Ask yourself one question. This is my favorite piece of advice from Pompian: “If you did not own this stock today, would you buy the same number of shares at the current price?” If the answer is no, you probably should sell.

My Take

I have seen loss aversion in myself. Growing up in an ex-USSR country, where losing anything felt catastrophic because you could not easily replace things, this bias was practically built into the culture. “Hold on to what you have” was survival wisdom. But in investing, that instinct can really hurt you.

The most important thing I took from this chapter is that loss aversion makes you take MORE risk, not less. That sounds backwards, but it is true. By holding onto a sinking ship, you are actually increasing the risk in your portfolio. And by selling your winners, you are removing the healthy parts.

Pompian says loss aversion “simply cannot be tolerated” in financial decision making. That is strong language for an academic book. But he is right. This bias does the exact opposite of what you want: it increases risk while reducing returns.

Previous: Recency Bias | Next: Overconfidence Bias

This is part of a series retelling “Behavioral Finance and Wealth Management” by Michael M. Pompian. Start from the beginning.