Facebook CEO Mark Zuckerberg reaped a gain of nearly 2.3 billion dollars (£1.5 billion) last year when he exercised 60 million stock options just before the online social networking leader's initial public offering (IPO).
The windfall detailed in regulatory documents filed saddled the 28-year-old with a massive tax bill. He raised the money to pay it by selling 30.2 million Facebook shares for 38 dollars (£24.50) apiece, or 1.1 billion dollars (£710,640 million), in the IPO.
Facebook's stock has not closed above 38 dollars since the IPO was completed last May. The shares gained 71 cents (46p) on Friday to close at 26.85 dollars (£17.34).
The 29% decline from Facebook's IPO price has cost Mr Zuckerberg nearly seven billion dollars (£4.5 billion) on paper, based on the 609.5 million shares of company stock that he owned as of March 31, according to the documents. His current stake is still worth 16.4 billion dollars (£10.6 billion).
Mr Zuckerberg, who started Facebook in his Harvard University room in 2004, has indicated he has no immediate plans to sell more stock.
The exercise of his stock options and his subsequent sale of shares in the IPO had been previously disclosed.
The proxy statement filed to announce Facebook's June 11 shareholder meeting is the first time that the magnitude of Mr Zuckerberg's stock option gain had been quantified.
The statement also revealed that Mr Zuckerberg's pay package last year rose 16% because of increased personal usage of jets chartered by the company as part of his security programme.
Mr Zuckerberg's compensation last year totalled nearly 2 million dollars (£1.3 million), up from 1.7 million dollars (£1.1 million) last year. Of those amounts, 1.2 million dollars (£775,243) covered the costs of Mr Zuckerberg's personal air travel last year, up from 692,679 dollars (£447,495) in 2011.
If not for the spike in travel costs, his pay would have declined by 17%. His salary and bonus totalled 769,306 dollars (£497,000) last year, as against 928,833 dollars (£600,000) in 2011.