We’ve confidentially submitted an S-1 to the SEC for a planned IPO. This Tweet does not constitute an offer of any securities for sale.— Twitter (@twitter) September 12, 2013
And fittingly with that tweet, Twitter confirmed widespread (but until now unsubstantiated) rumors that it plans to go public. For those wondering, the confidential submission appears to be under a new provision in last year's JOBS Act that lets firms with less than $1 billion in annual revenue keep their IPO filing under wraps at the outset of the filing process. (Quartz has more on the confidential process here.)
As TechCrunch notes, analysts expect Twitter to go public with a valuation of between $15 billion and $20 billion. For comparison, Facebooks IPO last year valued the social media giant at about $100 billion.