Anchoring on Purchase Price Mistakes

Intermediate | Published: 2025-12-28

Why It Matters

You bought a stock at $150. It drops to $70. Instead of asking whether the business still justifies a $70 valuation, you fixate on one question: "Will it get back to $150?" That fixation has a name -- anchoring bias -- and it quietly destroys portfolio returns.

TL;DR: Your purchase price is irrelevant to what a stock is worth today. Anchoring on it causes you to hold losers waiting for breakeven and sell winners too early. The fix: ask "Would I buy this at today's price?" If no, sell.

Anchoring on purchase price creates a predictable pattern: you hold deteriorating positions waiting for breakeven, you sell winners prematurely when they exceed your anchor, and you make decisions based on arbitrary past prices instead of current fundamentals. In a landmark housing market study, economists David Genesove and Christopher Mayer found that properties with higher purchase-price anchors stayed on the market 50% longer than comparable properties with lower anchors -- sellers simply could not accept prices below their mental reference point.

Definition and Core Concept

Anchoring is the cognitive bias where an initial piece of information disproportionately influences subsequent judgments, even when that information is irrelevant. Psychologists Amos Tversky and Daniel Kahneman first described it in 1974, showing that people start from an initial number and adjust insufficiently toward the true answer.

In investing, your purchase price becomes a powerful anchor. Two predictable distortions follow:

• Below anchor: "I'll hold until it gets back to my price" (waiting for breakeven)
• Above anchor: "It's up X% from my purchase -- time to sell" (premature profit-taking)

Both ignore the only question that matters: What is this worth today?

As behavioral finance researchers Hersh Shefrin and Meir Statman demonstrated in 1985, purchase price becomes the reference point for all subsequent gain/loss evaluations. You stop seeing a stock as "worth $50" or "overvalued" and instead see it as "down 20% from my cost."

How Anchoring Shows Up in Portfolios

Waiting for Breakeven on a Deteriorating Stock

You buy Peloton (PTON) in January 2021 at $150, investing $15,000. Your thesis: COVID tailwinds and digital fitness growth.

By June 2021, the stock falls to $120. You hold, waiting for $150. By September, growth slows and guidance gets cut -- stock at $100. By December, subscriber churn rises -- stock at $70. COVID tailwinds are reversing, gyms are reopening, and competition is increasing. Revised fundamentals suggest fair value of $40-60.

KEY INSIGHT: At every price decline, the rational question was "Would I buy this at today's price?" Instead, anchoring made you ask "Will it get back to $150?" -- a question the stock cannot answer.

You keep holding. By June 2022 the stock hits $40. By December 2023 it stabilizes at $30 -- an 80% loss. Your $15,000 is now $3,000.

The opportunity cost is even worse. Selling at $70 and reinvesting in the S&P 500 (which rose roughly 40% over that period) would have produced about $9,800 -- a $6,800 difference driven entirely by anchoring on a now-irrelevant purchase price.

The IPO Anchor Trap

Anchoring does not require owning a stock. Uber IPOs at $45 in May 2019. You watch it drop to $32 by August and buy, thinking "it's cheap -- down 29% from IPO." But you are valuing relative to an arbitrary IPO price set by investment bankers, not fundamentals.

During the COVID crash, the stock falls to $14. Now you are anchored on two prices ($45 IPO and $32 purchase), and "down from both anchors" feels like a screaming buy -- even though pandemic economics fundamentally changed rideshare demand. When it recovers to $60, you sell because "it's above both anchors." The stock continues to $70.

Markku Kaustia and Samuli Knupfer showed in 2008 that even IPO prices become anchors: investors who experienced positive returns from one IPO subscribed to future IPOs at higher rates -- the first price anchored their expectations.

Decision Rules to Break Anchoring

The Purchase Price Blind Test

Before any hold/sell decision, ask: "If I had this money in cash today, would I buy this stock at its current price?"

If the answer is no, the default is to sell -- unless you have a specific reason not to (tax timing, lockup period, high transaction costs).

Quarterly upgrade: Write a fresh investment thesis for each position without looking at cost basis first. Only after writing the thesis, check whether your current holding matches it. If the thesis says "sell" but you are holding, anchoring is controlling you.

Cost Basis Concealment

Hide purchase price from your brokerage display. Show shares held, current price, and total value. Hide cost basis, percent gain/loss, and dollar gain/loss. What you cannot see cannot anchor you. This matters most in tax-deferred accounts (IRAs, 401ks), where cost basis has no tax relevance anyway.

Fundamental Anchor Replacement

If you need a reference point, use one grounded in fundamentals -- P/E ratio versus 10-year average, price-to-sales versus sector median -- not arbitrary historical prices.

KEY INSIGHT: Replace the question "How far is this from my purchase price?" with "How does its valuation compare to historical and sector fundamentals?" This single substitution neutralizes the anchor.

Detection Signals

You are anchored if any of these apply:

• You use phrases like "waiting to get back to breakeven"
• Your sell targets cluster near round numbers close to your purchase price
• You evaluate stocks as "up/down X%" from purchase rather than cheap or expensive on fundamentals
• You cannot explain why you are holding a position without mentioning what you paid
• A different hypothetical purchase price would change your decision today

Quick Self-Test: The Reversed Anchor Exercise

Pick a position you currently hold. Imagine you had bought it at twice the current price. Would you sell to "cut losses"? Now imagine you had bought at half the current price. Would you sell to "take profits"? If different purchase prices produce different decisions, you are anchored. A fundamentals-based decision stays the same regardless of what you paid.

When Purchase Price Legitimately Matters

Purchase price is not always irrelevant. It matters for tax planning (determining short-term versus long-term capital gains), performance measurement (calculating returns), and regulatory reporting. The test: is the purchase price causing your decision, or just measuring the outcome? If causing, that is anchor bias. If measuring, that is legitimate use.

Related Articles

• Loss Aversion and How to Counter It
• Recency Bias During Sell-Offs
• Confirmation Bias in Stock Research
• Disposition Effect and Taxable Accounts

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References

Genesove, D., & Mayer, C. (2001). Loss Aversion and Seller Behavior: Evidence from the Housing Market. The Quarterly Journal of Economics, 116(4), 1233-1260.

Kaustia, M., & Knupfer, S. (2008). Do Investors Overweight Personal Experience? Evidence from IPO Subscriptions. The Journal of Finance, 63(6), 2679-2702.

Shefrin, H., & Statman, M. (1985). The Disposition to Sell Winners Too Early and Ride Losers Too Long. The Journal of Finance, 40(3), 777-790.

Tversky, A., & Kahneman, D. (1974). Judgment under Uncertainty: Heuristics and Biases. Science, 185(4157), 1124-1131.