Mental Accounting
An economic concept established by economist Richard Thaler, which contends that individuals divide their current and future assets into separate, non-transferable portions. The theory purports individuals assign different levels of utility to each asset group, which affects their consumption decisions and other behaviors.
Investopedia Commentary
The importance of this theory is illustrated in its application towards the economic behavior of individuals, and thus entire populations and markets. Rather than rationally viewing every dollar as identical, mental accounting helps explain why many investors designate some of their dollars as "safety" capital which they invest in low-risk investments, while at the same time treating their "risk capital" quite differently.
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See also: Anchoring, Behavioralist, Prospect Theory, Regret Theory, Risk Capital