As the 1549 papal conclave dragged on into a second and third month, Venice’s ambassador to the Vatican, Matteo Dandolo, was outraged by insider trading. “It is more than clear that the merchants are very well informed about the state of the poll,” he said, “and that the cardinals’ attendants in Conclave go partners with them in wagers, which thus causes many tens of thousands of crowns to change hands.”

Although the conclave was supposedly secret, Roman traders ran a thriving market in the streets around the Vatican trying to predict the winner. Odds shifted rapidly, and bettors appeared suspiciously well informed and perceptive. Everyone knew the race was wide open, and the original favorite in the crowded field, at 5-to-1 against (or 20% odds), was Cardinal Giovanni Maria del Monte. Ten weeks later, he was elected Pope Julius III as a compromise candidate, but only after opposing cardinals had brought forward a parade of options. Bettors on the streets helped the population understand who was leading, and by spotting early on that Julius might be the inoffensive candidate who would provoke the least opposition, they even guided the cardinals as they tried to break the deadlock.