When Joel Greenblatt went to Wharton Business School in the late 1970s, the theory of “efficient markets” was in full bloom, approaching the point of becoming dogma among the financial cognoscenti. To the young student, it all felt bogus.

Mr Greenblatt had already developed a taste for calculated gambles at the dog racing tracks. Reading the wildly fluctuating stock prices listed in newspapers also made him deeply sceptical of the supposed rationality of markets. One day he stumbled over a Fortune article on stockpicking, and everything suddenly fell into place.

“A lightbulb went off. It just made sense to me that prices aren’t necessarily correct,” recalls Mr Greenblatt, whose hedge fund Gotham Capital clocked up one of the industry’s greatest ever winning streaks until it was closed to outside investors in 1994. “Buying cheap stocks is great, but buying good companies cheaply is even better. That’s a potent combination.”