Kalshi and Other Prediction Markets Should Scare Sports Leagues (1)

Adhi Rajaprabhakaran began trading in prediction markets in summer 2020. Then a couple of years out of college, he started with bets on whether Joe Biden or Donald Trump would win that year’s presidential election, and on which states each would carry, buying yes-or-no contracts on Polymarket and PredictIt. By early 2021, Rajaprabhakaran was making his living as a trader and was busy trying to figure out when Jennifer Granholm would be sworn in as US secretary of energy.

Illustration: Alex Gamsu Jenkins for Bloomberg Businessweek

As part of that effort, he called an energy lobbyist. Two well-placed Senate staffers, the lobbyist told him, had ...