The U.S. Treasury said today it received an additional $1.8 billion in proceeds from General Motors Co.'s initial public offering after the company's underwriters exercised an option to sell more common stock, The Detroit News reported.

The additional sale brings the total money raised by the government in GM's IPO to $13.5 billion and reduces the treasury's stake in the automaker to 33 percent. That's down from 61 percent before the initial sale.

GM's underwriting banks had 30 days after the company's stock started trading on Nov. 18 to sell up to 15 percent more in common stock shares. The sale closed today, bringing the total number of common stock shares sold by the government to 412 million.

With the additional stock sale, GM's IPO in total brought in $23.1 billion, the world's largest IPO ever.

"General Motors' IPO is a testament to that company's turnaround and the significant progress we have made continuing to exit our investments and recover taxpayer dollars," said Tim Massad, acting assistant secretary for financial stability, in a statement.