General Motors Co. could file paperwork for its initial public offering as soon as Friday, CNBC reported Wednesday. The U.S. automaker is expected to file for an IPO worth up to $20 billion. At that size, it would be the biggest U.S. IPO since Visa Inc’s $19.7 billion offering in March 2008 and one of the biggest IPOs of all time.

The preliminary IPO filing was scheduled for mid-August, but GM Chief Executive Ed Whitacre’s comments during an industry conference last week that the company did not plan to file anything in the next two weeks led many to believe that the timeline had slipped.

Reuters earlier reported that GM was planning to file its prospectus early during the week of August 16.