Signaling the fast-growing popularity of online fantasy sports, Boston-based DraftKings, a daily fantasy sports website, said on Monday it has raised $300 million in its fourth round of funding, led by FOXSports. Major League Baseball, the National Hockey League, Major League Soccer, The Madison Square Garden Co. Legends,and previous backers Atlas Venture, DSTGlobal, GGV Capital, The Kraft Group, The Raine Group and Wellington Management also participated. The company will use the proceeds to continue building out its web and mobile products, launch internationally and explore new opportunities for vertical expansion. DraftKings has become the fastest-growing company in fantasy sports since its launch in 2012, having just registered its 100 millionth contest entry this month. It is expected to award well more than $1 billion in prizes in 2015, up from approximately $300 million last year, reports Potomac Tech Wire.