The Endowment Effect: Loving Your Losers

There is a peculiar phenomenon that affects nearly every investor. You buy a stock at $50 and it drops to $30. Now you hold it. You do not just hold it—you defend it. You tell yourself that it is a long-term hold. You tell your friends that you believe in it. You ignore bad news because you have already committed to it.

But if you did not own the stock and someone offered it to you today at $30, you would probably refuse. You would think: "Why would I want this stock? It is down 40% from its recent high and the business is struggling."

Yet because you own it, you value it differently. This is the endowment effect.

The endowment effect is one of the most consistently demonstrated findings in behavioral economics. When you own something, you value it more highly than you would if you did not own it. It is not rational valuation—it is simply a consequence of ownership.

In the context of long-term investing, the endowment effect keeps you stuck in positions that should be sold. You overvalue them precisely because you own them. And you rationalize this overvaluation with narratives: "It is a long-term hold," "I am waiting for it to recover," "The market does not understand the value."

Sometimes these narratives are true. But often, they are just the endowment effect talking.

Quick definition: The endowment effect is the cognitive bias where you overvalue items or investments simply because you own them, leading to reluctance to sell positions that should be sold and attachment to losing investments.

Key takeaways

• You value a stock 50% higher once you own it than you would if you did not own it
• The endowment effect creates artificial barriers to selling, keeping you in positions that underperform
• Underwater positions (positions in which you have a loss) are particularly vulnerable to the endowment effect
• The endowment effect is stronger when you have held the position longer (ownership compounds the bias)
• High-conviction positions can be justified, but they should never be justified primarily because you own them
• Selling does not mean admitting you were wrong—it means making the best decision with current information

The original research

Richard Thaler conducted a famous experiment in the 1980s where he gave some students coffee mugs. He then asked them to sell the mugs. He also asked other students (who did not own mugs) to indicate how much they would pay for a mug.

The students who owned the mugs demanded nearly twice as much money to sell them as the students who did not own mugs were willing to pay. Same mug. Different ownership status. Different valuation.

This experiment has been replicated hundreds of times with different objects—paintings, tickets, wine, stocks. The endowment effect is remarkably consistent. When you own something, you value it 30-50% more than you would if you did not own it.

In investing, this has profound implications. If you paid $100 for a stock and it drops to $70, you are down 30%. But if you did not own the stock and someone asked you whether you would buy it today for $70, you would ask: "Do I still think it is worth more than $70?" If the answer is no—if you would not buy it today at $70 given current information—then the endowment effect is keeping you in a losing position.

The relationship to sunk costs

The endowment effect is closely related to the sunk cost fallacy, but they are not identical. The sunk cost fallacy is the tendency to continue investing in something because you have already invested in it. The endowment effect is the tendency to overvalue something because you own it.

A sunk cost decision sounds like: "I paid $100 for this stock and it is now worth $70. I am down $30, so I am going to hold it until I break even." This is irrational because the $100 is already spent. The question is whether the stock, at its current price and given current information, is a good investment. The past purchase price is irrelevant.

An endowment effect decision sounds like: "This stock is worth $100 to me, even though the market is pricing it at $70." You genuinely, psychologically feel that you need more money to sell it than the market is offering. The market thinks it is worth $70. You think it is worth $100. The difference is the endowment effect.

Both biases lead to the same outcome (holding positions you should sell), but the psychological mechanism is slightly different.

Why the endowment effect is so powerful

The endowment effect works because ownership creates a sense of possession, identity, and attachment. When you own something, it becomes part of your mental portfolio. You have unconsciously decided that this is "your stock" and you have a relationship with it.

This is amplified by narrative. If you bought Apple in 2010, you have probably told yourself a story about why it is great: "It is the most innovative company in the world," "It has a moat," "The ecosystem is unbeatable." By telling yourself this story, you have built an emotional attachment to the position. It is not just a portfolio holding—it is a story you believe in. Selling would feel like admitting the story was wrong.

The endowment effect is also stronger the longer you hold something. A stock you bought five years ago is psychologically more yours than a stock you bought last week. You have collected dividends, survived crashes, and seen the narrative play out. Your ownership feels deeper.

And crucially, the endowment effect is stronger for underwater positions. You are more attached to a stock that is down 30% than to a stock that is up 100%. This is partly because selling at a loss feels like admitting defeat, and partly because the downside has given you time to construct narratives about why you will be right in the long run.

How the endowment effect becomes a trap

Here is the typical progression:

1. You buy a stock with conviction (you think it is good)
2. The stock declines (the market disagrees with you)
3. The endowment effect kicks in (you value the stock more highly because you own it)
4. You hold the stock expecting recovery
5. Either: a. The stock recovers and your conviction was justified (you were right, but you might have been lucky) b. The stock continues to decline and becomes a permanent loss (the endowment effect trapped you in a bad position)

The problem is that at step 3, you cannot distinguish between being right and being trapped. The endowment effect makes both scenarios feel the same. You feel attached to the position and confident in the narrative.

This is why it is so important to have rules about selling that do not depend on your attachment to the position. If you buy a stock expecting 20% annual returns over 5 years, and after 2 years it is down 20%, the thesis is broken. You should sell, regardless of how attached you are to it.

The journal of losses

One way to combat the endowment effect is to keep a journal of every sell decision. Write down:

1. Why you originally bought it
2. Why you are selling it
3. How much you gained or lost
4. What you learned

By doing this, you create an external record that is not distorted by the endowment effect. You are forced to articulate reasons for selling that go beyond "the narrative still feels good."

Over time, you will notice patterns. Maybe you are good at selling winners but bad at selling losers (classic disposition effect). Maybe you are good at selling thesis violations but bad at selling positions that just underperform. Maybe you are terrible at selling at all (a sign of strong endowment effect).

This journal becomes valuable feedback that helps you overcome the endowment effect. It forces you to be honest about your decisions in a way that you cannot be when you are just managing your portfolio mentally.

Distinguishing conviction from endowment effect

Not every position you hold for a long time is a victim of the endowment effect. Some positions are held for legitimate reasons: you genuinely believe in them, they have been profitable, and they still have a good risk-reward ratio.

How do you know the difference? Ask yourself:

• If I did not own this stock, would I buy it today at its current price? If the answer is no, the endowment effect may be driving your holding.
• Can I articulate why I own this in 30 seconds without mentioning my cost basis? If you need to refer to what you paid for it, the sunk cost fallacy is at play.
• Is there a specific thesis that I update as new information arrives? If your thesis has not changed in a year, either the business is unchanged (which is rare) or you are not updating your thesis.
• Would I buy more at the current price? If not, you are overvaluing it relative to the market.
• What would need to happen for me to sell? If the answer is "it would need to recover to my purchase price," you are trapped by the endowment effect.

Real-world examples

Consider a case study: A 2005 investor bought Lehman Brothers. It was a respected, established company with a 150-year history. The investor was probably attached to it because it was "Lehman Brothers"—a household name, a marker of quality.

By 2008, Lehman had serious problems. But the endowment effect made the investor hold. "Lehman Brothers has survived every crisis for 150 years," the investor might think. "Why would it fail now?"

It failed. The investor lost everything. The endowment effect to a respected brand kept them holding through the decline to zero.

A more recent example: many investors held Valeant Pharmaceuticals through its collapse. Valeant was a growth stock, a compounder story. Investors felt smart holding it and telling others about it. When it started to decline, the endowment effect kept them holding. By the time they sold, they had lost 90%.

In contrast, investors who sold winners like Apple and Microsoft in the early 2000s after they declined, only to watch them become 100x+ multibaggers, were victims of the endowment effect in the opposite direction. They undervalued the stock relative to its actual potential because they no longer owned it and could not see it as "their stock."

Common mistakes

1. Holding losing positions to avoid admitting you were wrong. You are not admitting you were wrong by selling. You are making the best decision with current information.

2. Assuming that your attachment to a position means it is a good investment. Your emotional attachment is a signal of the endowment effect, not a signal of investment quality.

3. Using tenure as a reason to hold. "I have owned this for five years" is not a reason to hold it. "The thesis is still intact" is a reason.

4. Overweighting narrative over evidence. You have built a story around why you own this position. But if the evidence is contradicting the story, the story may be wrong.

5. Not selling losing positions that have broken theses. Your original thesis for buying is irrelevant if the thesis is now broken. Sell it.

FAQ

Q: How do I distinguish between the endowment effect and genuine conviction? A: If you would not buy the position today at the current price given all available information, the endowment effect is likely at play. Write down your thesis without referring to your cost basis.

Q: Is it ever reasonable to hold a stock just because I have owned it for a long time? A: No. Tenure is not a reason to hold. Fundamental reasons are reasons to hold.

Q: Should I sell everything I have lost money on? A: No. You should sell if your thesis is broken or if your risk-reward is no longer favorable. Some losing positions can still be good holds if the thesis is intact.

Q: How do I avoid the endowment effect when I have a winner? A: Ask yourself: "Is this position worth this percentage of my portfolio, or am I holding it larger because of the endowment effect?" Rebalance accordingly.

Q: Is there a way to be attached to positions AND make good decisions? A: Yes. Keep your attachment at the narrative level (you believe in the business) but separate it from your holding decision (you are willing to sell if the thesis breaks or risk-reward becomes poor).

Related concepts

• Sunk cost fallacy: The tendency to continue investing based on past investment rather than future prospects
• Disposition effect: The tendency to sell winners too early and hold losers too long
• Mental accounting: The tendency to evaluate investments in isolation rather than as part of a portfolio
• Confirmation bias: The tendency to seek information that confirms existing positions

Summary

The endowment effect is the bias that makes you love your losers and hold them longer than you should. When you own something, you value it 30-50% more than its market price simply because you own it. This is not rational valuation—it is a consequence of ownership.

The solution is to separate your emotional attachment from your holding decision. Ask yourself: "Would I buy this today?" If the answer is no, the endowment effect is at play. Write down your thesis without mentioning cost basis. Keep a journal of selling decisions. And remember: selling does not mean you were wrong. It means you are making the best decision with current information.

Next

Learn about anchoring to past prices, another bias that keeps you stuck in positions: Anchoring to Past Prices