The flotation, expected in May, could see Facebook raise $10bn (£6.4bn), meaning that the company could be valued as much as $100bn.
Practically, you can still buy and sell Facebook stock. However Facebook's lawyers need a breather to examine the full list of its shareholders before taking on more trades. The move could well, then, be indicative that Facebook is preparing an S-1 filing, the US Securities and Exchange Commission (SEC) paperwork used by public companies to register their securities.
Starting gun fired?
Facebook would need to release its main financial figures and performance to the SEC by the middle of February if it is to float in the third week of May - as many predict it will.
Recently Facebook's chief operating officer, Sheryl Sandberg, claimed that Facebook added $15.3bn to the value of Europe's economy last year. Sandberg, alluding to a Deloitte study the company commissioned, said the social media site was much more about "fun things with friends".
Increased UK productivitySandberg says many European business are using the site to build brand identity, supported by many Facebook apps from technology manufacturers (the so-called 'app economy'). Plus the company was responsible for creating 232,000 jobs in Europe, she said.
And the UK? Facebook reckons the UK economy benefits by around £2bn a year and 35,000 jobs. But are these 35,000 'extra' jobs unique to Facebook? Or could any old internet company have claimed that space regardless? That's unclear.
Oh, and how much does Facebook cost UK productivity? Just wondering.