Regeneron's ($REGN) hot-selling eye drug Eylea has done a lot in its short life, including post $1.4 billion in 2013 U.S. sales--and make the company's veteran CEO, Len Schleifer, into a billionaire. As Forbes' Matthew Herper calculates, Schleifer's Regeneron stake comes out to $600 million at its current share price, with exercisable options worth more than $300 million. Combine those figures with other personal assets, and he's past the $1-billion threshold. And with promising prospects in Regeneron's pipeline, that has the potential to keep on growing. Story | More