Two Israelis on Monday became the first people charged with using classified information to earn money on the online betting site Polymarket.

Polymarket, an online gambling website that allows users to bet on virtually anything, has become best known for its prediction markets on major world events. Concerns about insider trading among officials have grown along with the market’s popularity, and on Thursday, the first known charges against people who used classified information to enrich themselves on Polymarket were unsealed.