Sunk Cost Trap

DEFINITION of 'Sunk Cost Trap'

The tendency of people to irrationally follow through on an activity that is not meeting their expectations because of the time and/or money they have already spent on it. The sunk cost trap explains why people finish movies they aren’t enjoying, finish meals that taste bad, hold on to investments that are underperforming and keep clothes in their closet that they’ve never worn. The sunk cost trap is also called the Concorde fallacy after the failed supersonic Concorde jet program that funding governments insisted on completing despite the jet’s poor outlook.

BREAKING DOWN 'Sunk Cost Trap'

Individuals, businesses and governments fall into the sunk cost trap when they base their decisions on past behavior and a desire to not waste the time or money they have already spent, instead of cutting their losses and making the decision that would give them the best outcome going forward. People are reluctant to admit, even to themselves, that they have wasted resources on a past decision. Changing directions is viewed, perhaps only subconsciously, as admitting failure. As a result, people tend to stay the course or even invest additional resources in a bad decision in a futile attempt to make their initial decision seem worthwhile.
Here is an example of the sunk cost trap in action:
Jennifer buys $1,000 worth of Company X’s stock in January. In December, its value has dropped to $100 even though the overall market and similar stocks have risen in value over the year. Instead of selling the stock and putting that $100 into a different stock that is likely to rise in value, she holds on to Company X’s stock, which in the coming months becomes worthless.
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