Hedge fund billionaire Leon Cooperman is a stockholder in Green Thumb Industries, a publicly-traded marijuana cultivator and dispensary operator. Cooperman confirmed to Business Insider he invested in GTI personally, rather than through his firm, Omega Advisors. Hedge fund billionaire Leon Cooperman is investing in the marijuana industry. He's the biggest name so far to purchase stock directly in a marijuana cultivator. Cooperman posed a series of detailed questions to Green Thumb Industries (GTI) CEO Ben Kovler during the company's Q2 earnings call on Tuesday afternoon.