CITY brokers have never enjoyed the best of reputations. The popular image is of a brash and boastful twentysomething with more money than sense or sensitivity.

But now a study by a group of eminent American academics suggests that star performers on the stock market may be even worse and could best be described as “functioning psychopaths”.

In a study of investors’ behaviour, the team from three US universities suggest that people with brain damage can make better financial decisions than the rest of us.

Market traders may feel slighted, but this study comes from the growing field of neuroeconomics, which investigates the mental processes that drive financial decision-making.

The experts found that emotions can make investors play it too safe. They claim the emotionally impaired are more willing to gamble for high stakes.

The US team found that people with certain brain injuries which suppress their emotions could make the best stock market traders. They took a selection of 41 people of normal IQ, 15 of whom had suffered lesions on the areas of the brain that affect emotions, and made them play a simple investment game.

Those with brain damage significantly outperformed those without, the researchers from Stanford Graduate School of Business, Carnegie Mellon University and the University of Iowa found.

The key was the fear that stopped those with “normal” brains from taking even the most sensible of risks.

Antoine Bechara, an associate Professor of Neurology at Iowa, suggested that successful investors in the stock market might plausibly be called “functional psychopaths”.

These are individuals either much better at controlling their emotions or, perhaps, not experiencing them with the same intensity as others.

Baba Shiv, of Stanford, added chillingly: “Many CEOs (chief executive officers) and many top lawyers might also share this trait.

“Being less emotional can help you in certain situations.”

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