Endowment Effect

What is the endowment effect?

The endowment effect is the tendency to value something more once it is yours. The same mug can look like a $2 purchase to a buyer and a $5 possession to its owner.

In a classic mug experiment summarized by Kahneman, Knetsch and Thaler (1991), median sellers required $5.25 while median buyers offered $2.25–$2.75. The researchers used other trading tasks to address transaction costs and examined alternatives such as income effects. The experimental controls help isolate the effect in those trading tasks.

The comparison is often expressed as willingness to accept (WTA), a seller’s required compensation, versus willingness to pay (WTP), a buyer’s offered amount.

How it works

Loss aversion is one influential explanation: relinquishing an owned item can be evaluated as a loss. But loss aversion is not the only possible explanation for a gap between buying and selling prices. Plott and Zeiler (2005) found no mug valuation gap with modified procedures and extensive training. Fehr, Hakimov and Kübler (2015) subsequently found a persistent gap while trying to replicate that result. The disagreement makes the experimental procedures part of the story.

Applied example

Imagine spending two weeks inside a project-management tool, adding your tasks, templates and team settings. By the end, it may feel like yours. Giving it up can feel different from declining a product you have never used. That is a plausible endowment-effect explanation for staying. But you have also learned the tool and put work into it. To find out whether ownership itself changes willingness to pay, you need to separate that feeling from the practical cost of starting over.

Why it matters

Ownership can change how a trade feels. That matters for pricing, negotiation and product trials. It also gives you a testable question: do people value the same thing differently when it is already theirs? A high trial-conversion rate, on its own, cannot answer it.

Sources and further reading

• Thaler, R. (1980): Toward a Positive Theory of Consumer Choice
• Kahneman, D., Knetsch, J. L. & Thaler, R. H. (1990): Experimental Tests of the Endowment Effect and the Coase Theorem
• Kahneman, D., Knetsch, J. L. & Thaler, R. H. (1991): Anomalies: The Endowment Effect, Loss Aversion, and Status Quo Bias