On Wednesday, 133 cardinals are expected to enter the Sistine Chapel to elect the next pope.

People worldwide are placing millions of dollars in bets over who they think will get the two-thirds majority required to become the Catholic Church’s next leader. Thousands are even playing “Fantapapa,” a pope fantasy football-type game.

People have been betting on who becomes the next pope for centuries, according to John Holden, an associate professor at Indiana University.

But “we've seen a much bigger expansion of betting on the pope globally, as sort of technology has gotten better and allowed word to spread quickly,” he said.

Though papal bets are not allowed in U.S. sportsbooks, many Americans are on Kalshi, a financial exchange and prediction market. Cardinal Pietro Parolin is the frontrunner there, which Victor Matheson, a professor at College of the Holy Cross said could be a good predictor.

“Betting markets and prediction markets actually do a pretty good job at estimating what's going to happen,” he said.

There is one thing markets can’t account for, though: “A really big factor that no one you know necessarily talks about — because it's hard to talk about, and you certainly can't bet on — is the role that the Holy Spirit plays,” said Father Tom Dailey with the Saint Charles Borromeo Seminary in Pennsylvania.

Because, he said, cardinals are meant to elect the person God wants to be the successor.