Joachim Andersen

Accelerated Learning

Endowment Effect: Why We Overvalue What We Own

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Two identical antique gold rimmed porcelain teacups on a dark walnut desk at night, one displayed on a burgundy velvet cushion under a glass cloche and the other resting plainly on the wood
The same cup seems more precious the moment it becomes mine.


The Endowment Effect is the tendency to value something more simply because you own it. The same object seems worth more when it’s mine than when it belongs to someone else, so I often ask a higher price to sell something than I would ever pay to buy it.

I notice it whenever I sell something second-hand. My old bike, sofa or camera seems worth far more to me than to anyone who answers my ad, and I am a little offended by their offers. Yet if I were the buyer, I would offer exactly what they do.

The essence of the Endowment Effect is to ask: “If I didn’t already own this, how much would I pay to get it?”


Origin: Mr. R and His Wine

The term was coined by the economist Richard Thaler in 1980. He described an economist, Mr. R, who had bought a case of good wine in the late 1950s for about $5 a bottle. A few years later, his wine merchant offered to buy it back for $100 a bottle. He refused, even though he had never paid more than $35 for a bottle of wine. The wine was worth more than $100 to keep, but less than $35 to buy, which made no sense in standard economics.

Thaler linked the effect to loss aversion, which was originally described by Daniel Kahneman and Amos Tversky. Once I own something, giving it up feels like a loss, and losses weigh more heavily than equivalent gains.


Key Concepts

  • Willingness to Accept vs. Willingness to Pay
    The price we demand to give something up is often much higher than the price we would pay to acquire it.

  • Ownership Creates Value
    Even brief or accidental ownership can raise how much we value an object, before we have any real attachment to it.

  • Reluctance to Trade
    Because owners value what they have more than buyers do, fewer trades happen than economic theory predicts.

  • Status Quo
    What we already have becomes our reference point, so anything that would change it feels like a loss.

  • Experience Matters
    People who trade often, and who expect to sell, seem to be much less affected.


Some Examples

  • The Mug and the Chocolate Bar
    In a 1989 experiment by Jack Knetsch, one class of students was given a coffee mug and another was given a chocolate bar, and each was then offered the chance to swap. Of those given a mug, 89% kept it, and of those given chocolate, 90% kept it. In a third class, where students simply chose between the two, 56% picked the mug. What people preferred depended almost entirely on what they had been handed first.

  • The Mugs That Would Not Trade
    In 1990, Daniel Kahneman, Jack Knetsch and Richard Thaler gave coffee mugs to half the students in a class and set up a market where they could trade with the other half. Economic theory predicts that about half the mugs should change hands, but far fewer did, again and again. In another experiment, with 77 students at Simon Fraser University, some were given a mug and asked at what price they would sell it, others were asked what they would pay, and a third group chose between the mug and cash. The median seller asked $7.12, the median buyer would pay $2.87, and the choosers, who were in exactly the same position as the sellers except that they had not been handed a mug, valued it at $3.12. Owning the mug for a few minutes was enough to more than double its value.

  • The Sports Card Traders
    In 2003, the economist John List studied people trading sports memorabilia at trading card shows. Inexperienced traders showed a strong endowment effect and were reluctant to swap the item they had been given. Experienced dealers, who bought and sold all the time, showed little or none, which suggests that the effect can be unlearned through market experience.

  • The Sofa I Wanted to Sell
    When I sold an old sofa, I set a price that I thought was fair given what it had cost and how much I had enjoyed it. Nobody bit. When I asked myself what I would pay for the same sofa from a stranger, the answer was less than half my asking price, and it sold within a day of lowering it.


Applying the Endowment Effect

Owning things is not a mistake, but letting ownership distort my judgment can cost me money, space and better options. This is the simple process I follow:

  1. Ask the Buyer’s Question
    Before I decide to keep something, I ask whether I would buy it today at its current price, which removes the feeling of giving something up.

  2. Check the Market
    I look at what similar items actually sell for, rather than what they cost me or what they mean to me.

  3. Delay Ownership
    I am careful with free trials, test drives and home try-ons, which are often designed to make me feel like an owner before I have decided.

  4. Separate Memories From Objects
    When I keep something for its memories, I ask whether a photo or a smaller keepsake would preserve them just as well. I often end up with just digital photos of the objects in the end.

  5. Think Like a Trader
    For investments and possessions I plan to sell, I try to treat them as a dealer would, as things to be valued rather than parts of myself.


Pitfalls and Limitations

  • The size of the effect depends on the procedure. In 2005 and 2007, Charles Plott and Kathryn Zeiler found that the gap between selling and buying prices, and the asymmetry in swaps, shrank or disappeared when experiments carefully controlled for misunderstandings and other procedural factors.

  • Its cause is debated. Some research, such as a 2009 study by Carey Morewedge and colleagues, suggests that the effect comes from ownership and attachment rather than from loss aversion.

  • Sentimental value is real. An heirloom may be worth more to me than to any buyer, and that is not a bias but a genuine difference in what it means.

  • It can protect good choices. A small attachment to what I have can stop me from constantly chasing something slightly better.


Related Mental Models

The Endowment Effect reminds me that owning something changes how I see it. By asking whether I would buy what I already have, checking what it’s really worth to others and thinking more like a trader, I can keep what truly matters and let go of what only feels valuable because it’s mine.



To learn more about mental models and philosophy,
check out: Wise: How to Attain a Deep Understanding of the World, History, Our Place in It, and How to Live Well



📚 Sources and References


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