So many zeroes! New documents filed on Friday have made public for the first time the huge bonanza that Facebook founder Mark Zuckerberg earned when he exercised some 60 million stock options before the company went public last May. The 28-year-old pocketed $2.3 billion, the paperwork says—such a windfall that he later had to sell more than 30 million shares of Facebook just to pay for the subsequent tax bill. The social network's stock has failed to stay at its IPO peak, but Zuckerberg is still worth some $16 billion. Also revealed today: Facebook COO and Lean In author Sheryl Sandberg pocketed $845 million last year through vested shares, stocks, salary, and a bonus.