The U.S. Treasury Department chose Citigroup Inc. and JPMorgan Chase & Co. to manage the sale of shares in General Motors Co., as the government works to disentangle itself from the biggest U.S. automaker following the $50 billion bailout that began in 2009, Bloomberg News reported yesterday. The department announced the selection of the banks in documents on its website. It holds about 300 million shares after selling 200 million to Detroit-based GM for $5.5 billion in December. The agency said then that it would sell off the rest of its 19 percent stake within 15 months, starting as soon as January.