Zuckerberg, who owns about 444 million shares of Facebook plus an option to issue another 60 million, said he would not be selling any of his stake within the next twelve months.

Zuckerberg’s plans were announced as Facebook shares crashed to an all-time low of $17.55 yesterday, amid concerns the lock-up periods which prevented early backers from selling their shares may soon push down the share price further.

Facebook shares rose nearly 2% in after-hours trading after the announcement, but have fallen over 50% since the company went public in May this year.

The shares were valued at just over $38 when the company listed and have steadily fallen since then.

Peter Thiel, a venture capitalist and one of Facebook’s earliest backers sold 20.1 million shares last month according to reports, cashing in most of his stake in the firm, after the first lock-up period ended.

Analysts and investors have been concerned about the firm’s ability to generate revenue from users, with particular fears about how to target users who access it through mobiles.

The decreased screen space on these devices means it is difficult to place adverts.