Bill Ackman is poised to sell $290.5 million in stock back to Universal Music Group after a rejected takeover offer.

Bill Ackman plans to sell Pershing Square's 4.5% UMG stake after the music giant's board rejected his $64-65 billion takeover bid as fundamentally

The sale will end a tumultuous five-year relationship between Ackman and the world's largest music company.