Free course · Module 9
Loss Aversion and the Disposition Effect
Understand why taking a loss feels difficult, then learn to judge a holding by its future rather than your entry price.
Editorial review pending. Author and reviewer attribution await confirmation. · Updated 15 Oct 2026 · How we check lessons
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Idea 1 of 4
Separate the feeling from the forecast.
The same dollar change can feel different depending on its direction. Loss aversion describes greater sensitivity to losses than to equal gains. Prospect theory evaluates outcomes around a reference point, which an investor may treat as the price paid. Source 1.
The disposition effect is a related pattern: readily taking profits while resisting losses. Loss aversion is one possible explanation, alongside beliefs, regret and mental accounting; it is not a complete diagnosis of every hold or sell decision.
The reference point can shape your reaction without changing the investment’s prospects.
Does every loss hurt exactly 2.25 times as much?
Notice the feeling, then investigate the decision.
Idea 2 of 4
Understand what the evidence measures.
Brokerage records show a measurable preference for realizing gains. Odean’s 1998 study examined 10,000 accounts from 1987 to 1993. The full-year proportion of gains realized was 14.8%, versus 9.8% for losses. These are aggregated opportunity-based ratios, not the percentage of accounts or a daily sale probability. Source 2.
The gain-realization ratio was about one-and-a-half times the loss-realization ratio.
What do these ratios and later returns actually show?
A historical pattern is a reason to question your process, not a trading signal.
Idea 3 of 4
Review the holding from today’s price.
Your purchase price is part of your history, not a promise of recovery. Suppose you bought at $50 and the share now trades at $30. The price is down 40%. Getting back to $50 requires a 66.7% rise from today’s lower base. Waiting does not guarantee that return.
Ask whether the holding still fits your evidence, valuation, risk and portfolio plan. The “would I buy it today?” question can expose anchoring, but tax costs, transaction costs and portfolio constraints also matter. A “no” is a prompt to review, rather than an automatic sell order.
How do US capital-loss deductions work?
Why does the wash-sale window extend both ways?
Consider today’s evidence and the costs of acting, including tax rules.
Idea 4 of 4
Build a rule you can revisit.
Make the review process concrete. Before a practice purchase, write why the investment could work, what evidence would weaken that view and when you will review it. Use the same process for winners and losers.
Change the reference point
Hypothetical · no tradeThe recovery percentage uses today’s price as its base. It does not predict that recovery.
- Compare $50 to $30, then $50 to $25. Explain why a percentage loss and its recovery percentage differ.
- Cover your entry price. Write what evidence would support holding the investment today and what would challenge it.
- Choose a review date and record the reasoning. Revisit that reasoning rather than treating “back to my price” as the goal.
Use virtual practice to record decisions; no real trade is required. This calculator only compares prices and excludes dividends, tax and costs. Local practice and reading ticks do not record LMS completion.
What belongs in a useful decision journal?
Use the same evidence standard for a winner and a loser.
Quick check
Three quick checks. Feedback straight away.
In Odean’s 1998 study, what did investors do for most of the year?
Choose an answer to see the explanation.
In a US taxable account, you sell all 100 shares at a $2,000 loss on March 3, then buy 100 identical shares in that taxable account on March 20. What happens to the loss?
Choose an answer to see the explanation.
A US single filer has a $5,000 net capital loss after offsetting all capital gains and sufficient other income. How much can generally reduce other income this year?
Choose an answer to see the explanation.
Why is the price you paid a poor guide to what comes next?
Review your takeaway card and the learning path
- Name the feeling. An uncomfortable loss does not predict the next return.
- Read the evidence correctly. Study ratios are not individual stock forecasts.
- Review from today. Entry price matters for records and taxes, not a guaranteed recovery.
- Use a process. Write reasons, review the evidence and account for costs.
Reading markers and these practice checks stay on this device. They do not mark the LMS lesson complete.
Sources and assumptions
- Nicholas Barberis, Thirty Years of Prospect Theory, Yale working paper, November 2012. Reference points, loss aversion, the 1992 coefficient and limits of the explanation.
- Terrance Odean, Are Investors Reluctant to Realize Their Losses?, Journal of Finance, 1998. Table I realization ratios and Table VI subsequent returns.
- IRS Topic 409, Capital gains and losses. US individual capital-loss deduction limits and carryforward.
- IRS Publication 550, Investment Income and Expenses. Wash-sale window and taxable versus IRA replacement basis treatment.
Sources checked 15 October 2026. Research figures are historical. Price examples and the local calculator are hypothetical and exclude dividends, fees and taxes. Tax discussion concerns US individual taxable investments and is general education. Native LMS completion is separate from local practice.
StockEducation provides general education, not personal financial, tax or legal advice. Nothing here recommends a specific security. Investing involves risk, including loss of money you invest.
