Anchoring to Past Prices

You bought Apple at $150 per share. Today it is trading at $180. You feel good about the position—you are up 20%. But then you remember: last year it traded at $200. Suddenly, the $180 price does not feel as good. It feels like you have a $20 loss per share even though you are actually up $30 from your purchase price.

This is anchoring to past prices, and it is one of the most insidious cognitive biases in investing.

Anchoring is a fundamental cognitive bias where your brain "anchors" to an initial piece of information and then adjusts from that anchor when making subsequent decisions. In investing, the initial anchor is typically your cost basis—the price you paid for the stock.

Every decision you make about that stock is then filtered through the anchor. If the stock is below your cost basis, you see it as a loss, even though that historical purchase price has zero relevance to whether the stock is a good investment today. If the stock is above your cost basis, you feel like you are winning, even if the stock is actually overvalued at the current price relative to future fundamentals.

Your cost basis should be entirely irrelevant to your investment decisions. The question is not "did I pay a good price?" The question is "is this a good price right now?" But anchoring forces your brain to use the historical price as a reference point.

Quick definition: Anchoring to past prices is the cognitive bias where you fixate on the price you paid for a stock (cost basis) and use this as a reference point for all future valuation decisions, preventing objective assessment of current value.

Key takeaways

• Your purchase price is cognitively sticky and becomes an anchor that distorts all future valuation decisions
• Stocks below your cost basis feel like losses even when they are objectively good buys at the current price
• Stocks above your cost basis feel like wins even when they are overvalued at the current price
• Anchoring makes you more likely to hold losing positions (waiting to break even) and sell winning positions prematurely
• The strength of the anchoring effect increases the longer you hold the position and the larger the loss or gain
• Conscious awareness of anchoring is necessary but often not sufficient to overcome it

The original research

Amos Tversky and Daniel Kahneman's seminal work on anchoring showed that even when people know an anchor is random and irrelevant, it still affects their decisions.

In one experiment, they spun a wheel that could land on any number from 1 to 100. The wheel was rigged to land on either 10 or 65. They then asked people to estimate the percentage of African nations in the UN. People whose wheel landed on 10 gave much lower estimates than people whose wheel landed on 65. The wheel had no relevance whatsoever to the UN question. Yet it anchored people's estimates.

In investing, your purchase price is like the wheel. It is arbitrary from the perspective of current valuation. You paid $100 for a stock in 2015. Today it is 2025. The price in 2015 has zero relevance to whether the stock is a good buy at today's price. Yet your brain uses 2015's price as an anchor, distorting your current decision-making.

The cost basis trap

Here is how anchoring creates the cost basis trap:

You buy a stock at $100. Your cost basis is $100. This is your anchor.

Scenario A: The stock drops to $70. You are now down 30%. Your brain does not see this as "the stock is trading at $70, is that a good price?" It sees this as "I am down $30 per share." The loss hurts (loss aversion), and you hold the stock hoping to break even at $100. But this is irrational. If the stock is worth $60 on fundamentals, it is overpriced at $70. If it is worth $80 on fundamentals, it is underpriced at $70. Your cost basis of $100 is irrelevant to the correct answer.

Scenario B: The stock rises to $150. You are now up 50%. Your brain sees this as a win and you feel good about the position. But if the stock's intrinsic value is $140, it is overvalued at $150. If the stock's intrinsic value is $170, it is undervalued at $150. Again, your cost basis of $100 is irrelevant.

In both scenarios, you should be making decisions based on current price versus current value, not based on the historical cost basis.

But anchoring makes this nearly impossible. Your brain is psychologically "stuck" to the $100 anchor. All prices are evaluated relative to $100. Below $100 feels bad. Above $100 feels good. This emotional valuation distorts your rational decision-making.

The break-even bias

One of the most destructive manifestations of anchoring is the break-even bias: the tendency to hold losing positions far too long waiting for them to return to your purchase price.

You bought Intel at $60. It falls to $40. You are down $20 per share. Instead of asking "Is Intel a good buy at $40?" you ask "When will Intel get back to $60?" This is anchoring. You are hoping to break even on your psychological anchor, not because $60 is a good exit price.

In some cases, the stock never recovers. It declines to $20, then $10. All the while, you are holding and hoping to get back to $60. If you had simply asked "Is this a good investment at $40?" and answered no, you would have sold and moved the money to a better opportunity.

The break-even bias is one of the primary ways anchoring destroys returns. You hold losing positions too long, miss new opportunities, and finally exit when you are forced to acknowledge that the recovery is not coming.

The flip side: premature profit-taking

Anchoring also causes the opposite problem: selling winners too early.

You buy a stock at $100 and it rises to $150. You are up 50%. Your anchor says "I paid $100." The current price of $150 is well above your anchor. You feel like you have "won" and you want to take your profits.

But if the stock's intrinsic value is $200, it is still a good buy at $150. If you sell because you are up 50% relative to your cost basis, you are selling a position that should be held. The stock goes on to $250 and you missed the doubling.

This is the disposition effect combined with anchoring: you hold losers waiting to break even, and you sell winners prematurely after hitting gains relative to cost basis. This is a one-way ticket to underperformance.

Why anchoring is so sticky

Anchoring is sticky because it is cognitive, not emotional. You cannot overcome it with discipline or willpower alone. Your brain automatically references the anchor even when you consciously know you should not.

You could be a sophisticated investor who knows about anchoring. You could read this article and fully understand the concept. And you would still feel a sting of pain when a position drops below your cost basis. You would still feel a surge of pleasure when a position rises above your cost basis. The cognitive anchor is there regardless of your knowledge.

This is because anchoring is not a mistake that you make consciously. It is a default mode of human cognition. Your brain uses anchors to reduce the cognitive load of evaluating prices. Instead of calculating intrinsic value from scratch (which is hard), your brain compares the current price to the anchor (which is easy).

The brain is lazy. It uses shortcuts. Anchoring is one of those shortcuts.

How to overcome anchoring

Since anchoring is cognitive rather than emotional, you need systems rather than discipline.

Stop looking at cost basis. Many brokerages let you hide cost basis. Do this. If you cannot see the price you paid, you cannot anchor to it. You can then evaluate the current price in isolation.

Use a "new investor test." Imagine you were a new investor with no position in the stock. Would you buy it today at the current price? If yes, hold it. If no, sell it. This strips away the anchor and forces you to evaluate the stock on its current merits.

Calculate intrinsic value independently. Before you look at the current price or your cost basis, calculate what you think the stock is worth. Then compare the current price to your intrinsic value calculation, not to your cost basis.

Reframe losses as opportunities. When a stock drops below your cost basis, your brain says "loss." Reframe it: "The stock is cheaper. It is on sale. Is the sale-price attractive?" This reframe separates the current valuation from the historical price.

Use a journal without referencing cost basis. When you evaluate positions for holding or selling, write down your thesis and decision without mentioning what you paid. This forces you to ground your decision in current fundamentals.

Set selling rules that do not reference price. Instead of "sell when it hits $150" or "sell when I break even," use rules like "sell if the thesis breaks," "sell if valuation exceeds intrinsic value by 20%," "sell if ROIC declines below 12%." These rules are anchored to fundamentals, not to historical prices.

Real-world examples

The classic example of anchoring destroying returns is a stock that crashes and never recovers. Enron is the ultimate case. Investors bought Enron at $80-90 before the 2001 collapse. The stock fell to $0. Many investors held all the way down, hoping to break even at $80. The anchor to their cost basis prevented them from recognizing the fraud and selling.

A less extreme example: Blockbuster Video. Investors who bought at $20 in the 1990s held through the decline to $0 in the 2000s, anchored to their cost basis, convinced that video rental was too important to disappear.

In contrast, investors who held Coca-Cola or Apple for 20+ years did not anchor to the price they paid in 2000. They anchored to fundamentals: the quality of the business, the competitive moats, the growth trajectory. These are better anchors than price.

Warren Buffett is famous for avoiding anchoring. When he buys a stock, he decides he is holding it forever (or until the thesis breaks). He does not think about cost basis. He thinks about the intrinsic value of the business and whether that value has changed.

Common mistakes

1. Using cost basis as the primary reason to hold or sell. Cost basis is irrelevant. Thesis and current valuation are relevant.

2. Holding losing positions to break even. The stock price when you bought it is now meaningless. Judge the position on current merits only.

3. Selling winning positions because you are "up" a certain percentage. Being up 50% does not mean the stock is overvalued. If it is still undervalued, hold it.

4. Anchoring to highest-ever prices. Many investors anchor not to their cost basis, but to the highest price the stock ever traded at. "Apple was $200, now it is $150, so I have a loss." This is even worse than anchoring to cost basis.

5. Using multiple anchors. You anchor to cost basis, then anchor to highest ever price, then anchor to "what it should be worth." Strip away all anchors except current price versus intrinsic value.

FAQ

Q: Should I ever care about cost basis? A: Only for tax purposes (calculating capital gains). For investment decisions, ignore it entirely.

Q: Is there any good reason to set a price target when you buy a stock? A: Price targets can be useful if they are based on future intrinsic value. But do not anchor to them. If the target is reached before the business case changes, re-evaluate rather than automatically selling.

Q: How do I avoid anchoring if I see my cost basis on my brokerage statement? A: Cover it up or hide the statement. Or configure your broker to not display cost basis. Do not let your brain see the anchor.

Q: Should I own a stock I bought at $100 that is now worth $50? A: Only if you would buy it at $50. Pretend you do not own it and evaluate: is $50 a good price? If yes, hold it (or buy more). If no, sell it.

Q: How do I explain this concept to someone who does not understand why cost basis does not matter? A: Ask them: "If you inherited a stock worth $50 and never paid for it, would you hold or sell?" If they would hold it, cost basis is irrelevant. If they would sell, they are anchoring to zero as a cost basis.

Related concepts

• Reference point: The point against which gains and losses are evaluated (typically the purchase price)
• Framing effect: The tendency to react differently to the same choice depending on how it is presented
• Sunk cost fallacy: The tendency to continue investing based on past investment
• Mental accounting: The tendency to evaluate investments in isolated categories rather than holistically

Summary

Anchoring to past prices is one of the most destructive cognitive biases in investing. Your purchase price becomes a psychological anchor that distorts every valuation decision you make. Below cost basis feels like a loss. Above cost basis feels like a win. Neither of these feelings has any relevance to whether the stock is a good investment at the current price.

The solution is to make cost basis invisible and evaluate stocks based on current price versus intrinsic value. Use a "new investor test"—would you buy this stock today at the current price? Separate your decision from historical anchors. Keep a journal that avoids mentioning cost basis. And remember: the price you paid last year is just a number that your brain latches onto. It has zero relevance to the correct investment decision.

Next

Learn how biased interpretation of information leads to poor decisions: Confirmation Bias in Stock Picking