In the two decades since then, I had been waiting for the end of Wall Street. The outrageous bonuses, the slender returns to shareholders, the never-ending scandals, the bursting of the internet bubble, the crisis following the collapse of Long-Term Capital Management: Over and over again, the big Wall Street investment banks would be, in some narrow way, discredited. Yet they just kept on growing, along with the sums of money that they doled out to 26-year-olds to perform tasks of no obvious social utility.

Eisman stuck to his sell rating on Lomas Financial, even after the company announced that investors needn’t worry about its financial condition, as it had hedged its market risk. “The single greatest line I ever wrote as an analyst,” says Eisman, “was after Lomas said they were hedged.” He recited the line from memory: “ ‘The Lomas Financial Corp. is a perfectly hedged financial institution: It loses money in every conceivable interest-rate environment.’ I enjoyed writing that sentence more than any sentence I ever wrote.” A few months after he’d delivered that line in his report, Lomas Financial returned to bankruptcy.

“Society is obsessed with the idea of talent and genius and people who are ‘naturals’ with innate ability,” says Ms. Dweck, who is known for research that crosses the boundaries of personal, social and developmental psychology.

“People who believe in the power of talent tend not to fulfill their potential because they’re so concerned with looking smart and not making mistakes. But people who believe that talent can be developed are the ones who really push, stretch, confront their own mistakes and learn from them.”

In this case, nurture wins out over nature just about every time.