Psychologie a chování
Mental Accounting: Why We Handle Money Illogically
Key takeaways
- Mental accounting is the tendency to assign different values to money depending on where it came from or what it is earmarked for.
- Money is fungible — a crown from a bonus is worth exactly the same as a crown from a salary.
- A typical manifestation: we spend dividends freely but guard the portfolio principal at all costs.
- Recognise where mental accounting is driving your decisions, and always evaluate the overall outcome.
Mental accounting is a psychological phenomenon in which we divide money into imaginary buckets and treat each bucket differently — even though every monetary unit should rationally carry the same value. The term was coined by economist Richard Thaler, who won the Nobel Prize for his research in behavioural finance.
How it manifests in investors
The most common expressions of mental accounting in investing:
- Dividends vs. principal: We treat dividends as "free money" and spend them more easily, yet selling an equivalent slice of the portfolio feels unacceptable.
- Earned money vs. windfall: We are careful with earned income, but spend unexpected windfalls (bonuses, prizes) without guilt.
- Fun account vs. investment account: We take more risk in a speculative "fun" account because we do not perceive it as "real" savings.
Why it is harmful
Money is fungible — a thousand crowns is a thousand crowns regardless of where it came from or which bucket it sits in. Mental accounting causes us to optimise each bucket separately while missing the overall picture. We hold loss-making shares because they are in the "long-term bucket," and simultaneously borrow for "short-term expenses" — the total financial outcome is worse than it would have been with a coordinated plan.
How to correct mental accounting
The key is conscious awareness and a focus on the whole. Before making a financial decision, ask: "How will this affect my overall balance sheet?" A clearly structured portfolio allocation with regular rebalancing also helps — rather than making ad hoc decisions about individual buckets, it sets a framework for how much should be where in total.
Mental accounting is closely linked to other cognitive biases — a full overview of the traps in the investor's mind is available in the article on 12 cognitive biases.
FAQ
What is mental accounting?
The psychological tendency to divide money into imaginary buckets and treat each differently — even though money is fungible. Described by economist and Nobel laureate Richard Thaler.
How does mental accounting harm investors?
The investor optimises each bucket separately instead of focusing on the overall outcome. Typically, dividends are spent freely while selling part of the portfolio is refused — even when the total financial result would be better.
How can I break free from mental accounting?
Regularly review your total net worth rather than the performance of individual accounts. Ask how each decision affects the overall balance. Fixed allocation rules help replace instinctive bucketing.