CHICAGO (AP) — Sports have become a big part of prediction markets . So big that even sportsbooks have moved into the business. The rapid growth of sports offerings on prediction markets — called event contracts — has captured the attention of the four major North American sports, along with the NCAA and other organizations. Kalshi and Polymarket are the two biggest platforms, but they have plenty of company. More are on the way, too. Some leagues have jumped on another revenue opportunity,