(Image source: money.msn.com) Shares of SeaWorld Entertainment Inc (NYSE:SEAS) are trading in the negative territory as a result of the Blackstone Group L.P. (NYSE:BX) revealing in a prospectus filing plans to sell 15 million shares. After the sell, Blackstone’s stake in SeaWorld will fall to 25 percent from 42.8 percent. Blackstone will gain $498 million from the sale. Currently, SeaWorld is experiencing significant headwinds after a documentary called “Blackfish” shed negative light on the company’s treatment of Orca Whales. The documentary has created huge backlash against the company. Many celebrities are waging boycotts against SeaWorld.