Refusing to Sell a Mistake

An investor purchases a stock at $50. The price falls to $20. The investor has lost $30 per share, roughly equivalent to his monthly income. The thought of "locking in" the loss is painful. Worse, selling at $20 feels like admitting the original analysis was wrong. So the investor holds, waiting for the price to rebound to $50.

But the company has declined further—earnings have been cut, debt is rising, and competitive pressures are intensifying. The business is now worth $15. The investor is now facing a potential 70% loss instead of the 40% loss he would have suffered by selling at $20.

The original $50 purchase price is sunk. It is gone, irretrievable, and should have no bearing on the current decision. Yet the investor clings to the sunk cost, hoping recovery will validate the original decision. This is the sunk cost fallacy in investing.

Quick definition: The sunk cost fallacy is the psychological error of basing current decisions on unrecoverable past costs instead of on the forward-looking economics of the investment.

Key takeaways

1. Sunk costs should be completely ignored in investment decisions — the $50 purchase price is irrelevant; only the current price and future prospects matter
2. Loss aversion and endowment effects drive the behavior — investors experience the pain of losses more acutely than equivalent gains
3. Admitting error is painful — selling a loss requires acknowledging that the investment decision was wrong, which is psychologically difficult
4. Holding creates false hope — waiting for a rebound allows investors to avoid admitting error while maintaining hope
5. Opportunity cost compounds — capital locked in a dying business could have been deployed in a thriving one
6. Most stocks that fall 50% don't recover — the rebound to the original price requires not just stabilization but growth, which is unlikely in a deteriorating company

The psychology of sunk costs

The sunk cost fallacy is deeply rooted in human psychology. In most of life, past investments should influence future decisions. If you've invested years in a career path, switching careers is expensive. If you've invested in a house, selling it has transaction costs. The sunk cost principle has served humanity well in most domains.

But in investing, sunk costs are truly sunk. There are no transaction costs to selling a stock (other than minimal brokerage fees). There are no switching penalties. The past purchase price has zero bearing on whether the stock should be owned today.

Yet investors routinely make decisions based on sunk costs:

• Holding a stock because they "need to recover the loss first"
• Averaging down because they're "getting a better price" (sunk cost rationalization)
• Refusing to sell because "I'm not willing to take the loss"

Each of these is sunk cost thinking dressed in different language.

Loss aversion and the value equation

Behavioral finance research by Daniel Kahneman and Amos Tversky shows that investors experience losses roughly twice as acutely as equivalent gains. Losing $10,000 is psychologically more painful than gaining $10,000 is pleasurable.

This asymmetry causes investors to avoid selling at a loss even when selling is the rational choice. The psychological pain of "locking in" a loss overrides the economic logic that holding a deteriorating investment will likely compound the loss.

Compounding the issue is the endowment effect: once we own something, we immediately value it more than we valued it before purchasing. An investor who bought a stock at $50 tends to think it's "worth" $50 even after it's fallen to $30. The endowment effect biases our valuation.

When does an investment warrant being held despite losses?

Not all losing positions should be sold immediately. Some stocks fall temporarily and then recover. The question is: when should an investor hold and when should an investor sell?

Hold if: The underlying business fundamentals remain intact, the loss is driven by temporary market pessimism, and the expected long-term return is still attractive relative to risk.

Example: A quality company falls 40% in a market panic despite unchanged fundamentals. If the business still generates attractive returns on capital, the loss is a buying opportunity, not a selling signal.

Sell if: The loss reflects new information about the business that changes your intrinsic value estimate downward, or the expected return is now inadequate to compensate for the risk.

Example: A company reports that revenues are declining faster than expected and debt is rising. The loss reflects real deterioration, not temporary pessimism. The expected future return is inadequate. Sell.

The critical distinction is whether the loss reflects investor emotion (a temporary mispricing that you can exploit) or real deterioration (new information that changes the business's prospects).

Sunk cost manifests in "double-down" averaging

Many investors respond to losses by "averaging down"—buying more shares at the lower price. The logic seems sound: "I was willing to pay $50; now I can buy at $30. That's a bargain."

But this logic is pure sunk cost thinking. The fact that you were willing to pay $50 in the past is irrelevant. The current question is whether the stock is worth $30 today.

If the stock fell from $50 to $30 because the business fundamentals deteriorated, then $30 might be an even worse valuation than $50 was. Averaging down compounds the mistake.

Averaging down is appropriate only if:

1. The original investment thesis was sound
2. New information has not changed the business's prospects
3. The price decline is driven by market pessimism, not new company-specific deterioration
4. You have positive expected return from this point forward

Most investors who average down fail to satisfy these conditions. They average down because they're emotionally committed to the original decision and hope for recovery.

The asymmetry of recovery

A stock that falls 50% (from $100 to $50) must rise 100% just to break even. A stock that falls 70% (from $100 to $30) must rise 233% to recover.

For most businesses in decline, these recovery rates are impossible. The company doesn't suddenly accelerate growth after falling 50%. Typically, decline continues.

Consider that among all stocks that fall 50% in value, what percentage subsequently return to their prior price? Academic research suggests it's fewer than 30%. The majority of stocks that decline sharply continue to underperform.

This asymmetry means that holding a stock waiting for it to "get back to my purchase price" is betting on an unlikely outcome. The capital would be better deployed in opportunities with higher probability of success.

Real-world examples

Enron (2001). Employees and early investors who held Enron stock as it fell from $90+ became increasingly committed to recovery. The stock would "bounce back," they believed. It didn't. The stock went to zero. Employees lost billions in retirement savings holding shares they couldn't emotionally bring themselves to sell.

General Electric (2009–2020). GE traded near $35 in 2009 as the financial crisis hit. Investors who bought at that "cheap" level were holding stock that traded near $5 in 2020. Those who sold at $30 in 2010 (a seemingly small gain but a selling opportunity) avoided the catastrophic 80% decline that followed. Those who held, waiting for the price to return to $35, suffered massive losses.

Sears (2010–2018). Sears traded around $50 in 2010 with investors confident that the retailer's scale and brand would allow it to compete with Walmart and Amazon. Shareholders who held waiting for $50 prices again held stock worth pennies by 2018. Investors who sold at $20 in 2015 (taking a loss) avoided the subsequent 95% decline.

The decision framework

When facing a losing stock position, ask these questions in order:

1. Would I buy this stock at today's price if I didn't already own it?

If the answer is no, sell. The sunk cost of the previous purchase shouldn't prevent you from selling an investment you wouldn't make today.

2. What is my estimate of intrinsic value today?

Compare the current price to your intrinsic value estimate. Is the margin of safety adequate given the risks?

3. What information caused the price to decline?

If the decline reflects real deterioration in the business (new competition, revenue decline, debt growth), sell. If it reflects market pessimism on unchanged fundamentals, consider holding.

4. What is my forward-looking expected return?

From today's price, what annual return do you expect over the next five years? Does it exceed your cost of capital plus a margin for risk?

5. What would I do if I had to deploy new capital today?

If you have $1,000 to invest, would you buy more of this stock or would you buy something else? If something else, you should sell the position.

Common mistakes

Mistake 1: Conflating "I was wrong before" with "I'm wrong now." Even if your original analysis was incorrect, the forward-looking decision about whether to hold should be based on current economics, not past mistakes.

Mistake 2: Averaging down without evidence of recovery. If you average down, ensure that the business fundamentals support higher returns, not just lower prices.

Mistake 3: Holding for a "catalyst" that may never materialize. Investors often hold losing positions waiting for a catalyst (new CEO, acquisition, turnaround). If the catalyst doesn't appear within 18–24 months, exit.

Mistake 4: Holding to avoid "locking in" losses. Every day you hold a deteriorating stock, you're "locking in" opportunity costs. Selling to redeploy capital is often the rational choice.

Mistake 5: Treating past prices as anchors. Your purchase price at $50 is anchoring your judgment. Ignore it and assess the stock on forward economics.

FAQ

Q: Is it ever smart to average down? A: Yes, if the investment thesis remains intact and the company's prospects haven't deteriorated. But this is rare. Most investors average down to avoid admitting error.

Q: How long should I hold a losing stock waiting for recovery? A: If you don't see evidence of business improvement within 18–24 months, the recovery thesis has likely failed. Exit and redeploy capital.

Q: Should I wait for the stock to recover to my purchase price before selling? A: No. This is pure sunk cost thinking. Sell when the forward economics no longer justify ownership.

Q: How can I distinguish between temporary pessimism and real deterioration? A: Monitor business metrics (revenue, margin, cash flow). If these are unchanged despite the price decline, the decline is likely driven by pessimism. If business metrics have deteriorated, the decline reflects reality.

Q: What percentage decline triggers a reassessment? A: A 20–30% decline should prompt reassessment. A 50%+ decline almost always warrants serious reconsideration of the investment thesis.

Related concepts

• Loss aversion — the psychological tendency to avoid losses more strongly than to pursue gains
• Endowment effect — the tendency to value things more highly once we own them
• Confirmation bias — the tendency to seek information that confirms existing beliefs and ignore disconfirming evidence
• Opportunity cost — the value of the next best alternative, often ignored by investors holding losing positions
• Anchoring bias — the tendency to rely too heavily on an initial piece of information (the purchase price)

Summary

The sunk cost fallacy is one of the most destructive psychological errors in investing. The past purchase price is irrelevant. Every investment decision should be based on forward-looking economics: Is the company worth more or less than the current price? Will it likely outperform alternative uses of the capital? Holding a stock waiting for it to return to your purchase price is emotional investing, not rational capital allocation.

The investor who can overcome sunk cost thinking—who can sell a loss quickly and redeploy capital to better opportunities—will outperform those who cling to mistakes.

Next

Beyond the psychology of selling individual positions, investors must also manage their portfolio as a whole. In the final chapter-14 article, we'll examine the dangers of averaging down across a portfolio of losing bets.