Twitter files for IPO - CBS News Twitter is getting ready to file for an initial public offering (IPO). A tweet from the micro-blogging company's Twitter account Thursday read, "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. Some estimates put the company's worth anywhere between $9 billion and $11 billion. Twitter CEO Dick Costolo said in January that he was cautious about filing an IPO because he didn't want Twitter to be a public company that must bend to shareholders' wishes. Costolo didn't take questions after speaking at TechCrunch Disrupt on Monday. He spoke about leadership during the brief presentation. Analysts have long expected Twitter to file for an IPO. The company has been working to boost ad revenue and advertising products. Twitter did not immediately respond to a request for further comment.