By early 2009, he had changed his own boyish look. Mr. Zuckerberg, who once sported sandals to major meetings, traded his daily uniform of a T-shirt and jeans for a button-down shirt and tie. 'This is a serious year,' he told employees, explaining how similar attire somehow gave prep-school students more gravitas.

He eventually found a solution to allow employees to cash out in mid-2009: Russian investors Digital Sky Technology purchased roughly $100 million in shares from employees and invested $200 million directly, giving DST a 3.5% stake in the company.

By opening the door to a single investor, he avoided increasing the Facebook's shareholder base. The move also pacified employees, who splurged on new homes, cars and lavish vacations.

At least one board member, venture capitalist and PayPal co-founder Peter Thiel, had been against the plan, according to people familiar with the matter, arguing the company should be more disciplined and turn a bigger profit with what it had.

But Mr. Zuckerberg pushed and Mr. Thiel acquiesced-as long as the terms were favorable. DST agreed to a whopping $10 billion valuation, barely diluting shareholders like Mr. Zuckerberg.

In February, Jim Breyer, a board member and an early Facebook investor, told a German audience of techies that Facebook wouldn't be going public in 2010.

Later that month, Mr. Zuckerberg, having grown weary of the topic, said in an interview, 'As a practice, we aren't going to comment on it.'

Meanwhile, the CEO has another, albeit modest, plan to help mollify employees. He promised to buy them a bigger gong.