G.M. Names First Female Chief Executive DETROIT - General Motors announced Tuesday that its chief executive, Daniel F. Akerson, would retire next month and be succeeded by Mary T. Barra, who would become the first woman to lead a major auto company. The elevation of Ms. Barra, 51, to the chief executive post is the latest dramatic change at the top of General Motors since its bailout by the federal government in 2009. G.M., the nation's largest automaker, said that Mr. Akerson, 65, would step down as chief executive and chairman on Jan. 15. His planned retirement was hastened, the company said, by his wife's recent cancer diagnosis. Ms. Barra has worked for G.M. for 33 years and was most recently the executive vice president of global product development. She is considered a critical player in the overhaul of company's vehicle lineups around the world. The G.M. board approved Ms. Barra's selection and named her a director of the company. "With an amazing portfolio of cars and trucks and the strongest financial performance in our recent history, this is an exciting time at today's G.M.," Ms. Barra said in the company statement. I'm honored to lead the best team in the business and to keep our momentum at full speed. Ms. Barra, who is married and the mother of two children, joined General Motors in 1980 as a co-op student in the company's Pontiac division. An electrical engineer by training, she worked in a variety of engineering posts and managed an assembly plant, among other jobs, before being named head of the company's human resources department in 2009. After being promoted by Mr. Akerson to head G.M.'s global product development in 2011, Ms. Barra set out to streamline the company's historically bureaucratic vehicle development process. She has been an advocate of reducing the number of global vehicle platforms that G.M. uses around the world, an approach that saves money and reduces complexity among its product lines. "G.M. is in more than capable hands, as we've seen some of the best products released under Mary Barra, who has helped oversee the development of their vehicles on a global scale," said Jack Nerad, an analyst with the auto-research firm Kelley Blue Book. The announcement of Mr. Akerson's retirement came a day after the Treasury Department said it had sold the last of the G.M. stock that taxpayers received in exchange for the government's $49.5 billion bailout of the company. Mr. Akerson was among the new directors that the government installed after the bailout. He became chief executive in 2010 and led the automaker through its initial public stock offering and subsequent turnaround. "I will leave with great satisfaction in what we have accomplished, great optimism over what is ahead and great pride that we are restoring General Motors as America's standard-bearer in the global auto industry," Mr. Akerson said. The choice of Ms. Barra as the next chief executive was not totally unexpected in Detroit, where she had been considered among a handful of internal candidates for the job. But by choosing a female C.E.O., the G.M. board underscored how the once lumbering automaker is embracing change and diversity. G.M. said that Mr. Akerson's successor as chairman of the board would be Theodore M. Solso, the former chairman and chief executive of Cummins, the engine manufacturer. The company also said that its chief financial officer, Dan Ammann, would become president of G.M. and assume responsibility for regional operations and global brand organizations. Mr. Ammann, 41, will retain the C.F.O. job until a successor is named. Other changes include the move of Mark Reuss, who had been chief of G.M.'s North American operations, to Ms. Barra's job as head of product development. Mr. Reuss had also been considered a candidate for the chief executive position. G.M. also announced that Stephen J. Girsky, who is a vice chairman of the company, would move to a senior advisory role until leaving the company in April. He will remain on the General Motors board.