What is Behavioral Finance?

By Lee Samaha – Updated Oct 8, 2025 at 2:37 AM EST

Key Points

Behavioral finance explores how psychology affects investing, notably via irrational decision-making.
Common biases like risk aversion and herd behavior can lead to suboptimal investment choices.
Using insights from behavioral finance can help investors counteract biases and improve strategies.

Investing isn't just about the numbers; it's about the people behind the numbers. It's also about understanding why the people behind the numbers act as they do.

Armed with some relatively simple concepts and understanding around behavioral finance and how people act, you can make better investments and potentially life-changing financial decisions. Let's take a look at behavioral finance and why it matters.

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Risk Management

The process of identifying, assessing, and mitigating potential threats to minimize their impact on an organization’s goals.

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Similarly, the concept of mental accounting, or assigning money into different mental accounts, can lead to irrational decision-making. This works in the sense that people are more willing to spend $50 to buy a theater ticket if they had lost $50 in cash than they are if they lost the ticket worth $50. The reason being that they mentally account for the price of going to the theater as now being $100 in the second case.

An investment example is how you treat a $1,000 profit after reducing a winning stock position. It has the same value as $1,000 you earned from working. There's no reason to mentally account for it any differently. But some people may treat the $1,000 profit differently and then speculate wildly with it because they've mentally accounted for it as bonus money.

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About the Author

Lee Samaha is a contributing Stock Market Analyst at The Motley Fool covering industrials, electricals, energy, materials, transportation, and infrastructure stocks. Prior to The Motley Fool, Lee was a Civil Engineer and Investment Manager. He holds a Bachelor of Civil and Structural Engineering from Southampton University and a Certificate in Investment Management from Chartered Institute for Securities & Investment. Lee first cut his investing teeth on The Motley Fool bulletin boards (commonly referred to as the “Fool Boards,”) and he’s infinitely grateful to all of the investors he learned from in this powerful investing community.

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Lee Samaha has no position in any of the stocks mentioned. The Motley Fool recommends Tapestry. The Motley Fool has a disclosure policy.