San Francisco: Facebook CEO Mark Zuckerberg has no intention to sell his stock for at least 12 months, said the social network company in a regular public filing. According to a memo with the US Securities and Exchange Commission (SEC) Tuesday, Zuckerberg will make none of his 504 million shares reach the market for at least 12 months, and he would have to inform SEC in advance if he wants to release any of his stake. Zuckerberg's Facebook shares, which were worth around $20 billion on its IPO day is currently worth about $8.9 billion. reported Xinhua. Meanwhile, Facebook extended the lockup expiration date, after which some employees will be able to sell their shares, to Oct 29 from Nov 14, when more than 1 billion shares will be free to enter the market. Some Facebook insiders, including co-founder Dustin Moskovitz and early investor Peter Thiel, have begun to sell their shares in the company. Moskovitz had sold 450,000 shares and Thiel had sold almost 72 percent of the shares he held from the Initial public offering of the Social network. More: Meet The Indian Girl Who Was Facebook's First Female Engineer