For the second time this week, General Motors has increased the proposed deal size for its upcoming IPO. Earlier Tuesday, GM filed with the SEC to increase the proposed price range to $32 to $33. Now, underwriters are indicating that selling shareholders plan to raise $15.5 billion by offering 478 million shares, a 31% increase from the originally proposed 365 million. Morgan Stanley, J.P. Morgan, and BofA Merrill Lynch are the lead underwriters on the deal, which is expected to price Wednesday for trading on Thursday.