General Motors filed for an initial public offering of stock on Wednesday, clearing a key hurdle toward repaying taxpayers for a controversial bailout just over a year after its bankruptcy.

Morgan Stanley, JPMorgan, Bank of America Merrill Lynch and Citigroup have been selected as the lead underwriters for the IPO by the top U.S. automaker.

GM’s initial filing with U.S. securities regulators did not say how many shares would be sold or give an expected price range for what will likely be one of the biggest IPOs ever.

GM filed for an IPO of up to $100 million. That does not represent the full amount that GM hopes to raise, people familiar with the situation have told Reuters. GM could raise up to $20 billion in its IPO, the people said.

Attention has increasingly focused on the amount the IPO will raise, and if it will be enough, as some suggest it should be, to repay taxpayers on the hook for the controversial bailout.

(Read More: CNBC)