SOUTHFIELD, Mich. – General Motors Chief Executive Officer Dan Akerson is planning a reorganization of the automaker that would move it away from long-entrenched regional authority toward a structure built on global functions, said two people familiar with the planning.

Power would shift from regional chiefs to global leaders in areas such as marketing, purchasing and product development, said the sources, who asked not to be identified because the matter is private. While details remain sketchy, the company is working to upgrade its accounting system to support the new organization, the people said.

The reorganization would be an extraordinary challenge for the world’s largest automaker. The basic idea is that global chiefs can make the company more nimble and efficient. Three years after GM restructured in a government-backed bankruptcy, Akerson is tackling something that flummoxed his predecessors for decades.

“Everyone knows that the changes need to be made,” said Dennis Virag, president of Automotive Consulting Group Inc. in Ann Arbor, Mich. Akerson’s efforts are hampered by the company’s size, history, complexity and his own lack of manufacturing experience, he said. The CEO, a Navy veteran, has mostly worked in telecommunications and private equity.

The automaker has truck assembly plant in Allen County and a foundry in Defiance, Ohio.

While GM has slid 35 percent since its initial public offering in November 2010, Akerson has expressed frustration about the company’s splintered fiefdoms and culture of slow-moving consensus.

Net income fell by 50 percent in the first half of the year as the company lost money in Europe and its U.S. market share slipped by 2 percentage points.

After GM took back the global sales crown last year, while earning a record $9.19 billion, Toyota led six months into 2012.