Blackstone, the world's largest buyout firm, took SeaWorld public in 2013 after acquiring it four years earlier for $2.3 billion. Blackstone sold its final block of shares this year, cementing a return of about 2.7 times its original investment. Blackstone also owned Merlin in the past. The private equity firm acquired the entertainment company in 2005, bolstered it with acquisitions, sold a stake to CVC Capital Partners in 2010 and exited its final position in 2015.