Mental Accounts and Sunk Costs
Thinking, Fast and SlowThis flow traces how people organize outcomes into emotional accounts and then protect those accounts at the expense of future value.
increasing
Bearing strength in each event
decreasing
Ticket in the Blizzard

Paid Tickets
The Red Balance
A fan who paid for a basketball ticket is more likely to drive through a blizzard.
Sunk Emotion
The rational irrelevance of the purchase price loses to the desire to avoid a negative account.
Disposition Effect

Winners Sold First
Personal Score
Investors enjoy closing accounts with gains and avoid admitting losses.
Wealth Cost
They sell promising winners while retaining weaker losers.
Project Escalation

Good Money After Bad
Corporate Failure
A company continues funding an underperforming project because prior spending feels like an account that must be recovered.
Agency Conflict
Managers protect their reputations with shareholders' resources.
The Tennis Club

Dead Loss Avoided
Painful Membership
A player continues using a club after developing tennis elbow.
Emotional Accounting
Playing in pain preserves the fee as a cost rather than admitting it is lost.
Broad Portfolio Thinking

Future Consequences
Beyond Purchase Price
A rational investor evaluates which asset will perform best from now onward.
Account Closure
Past costs matter emotionally but should not determine future allocation.
During the mental-account discussion
Later in Part 4
After the disposition discussion
Near the end of the mental-account chapter
Near the conclusion of Part 4