Rubin has already succeeded in partnering with stars from other leagues, such as Tom Brady, who, Rubin said, is an investor in Fanatics. But Rubin felt he had reached the point where his ownership stakes in professional sports teams were holding both him and his company back. “When we first bought the Sixers, Fanatics was only in the merchandise business. Now we have the trading card business and the gambling business,” he said. “By the end of the year, we’ll have individual contracts with thousands of players, and I’ll be taking bets on the Sixers.”