DETROIT - The chief financial officer of General Motors Co., who brought the company through a successful public stock offering and was once considered a candidate for CEO, is resigning as of April 1.

In a surprise announcement Thursday, GM said that Chris Liddell, 52, will be replaced by Treasurer Dan Ammann. Liddell has been on the job for just 14 months.

During a hastily arranged conference call with reporters, Liddell said he had no job lined up, but doesn't want to be a chief financial officer any longer. He said he had achieved his goals of pulling off GM's IPO, fixing its accounting problems and getting the company back on sound financial footing.

The move is another in a series of management changes that started soon after GM emerged from bankruptcy protection in July of 2009. The company has had four CEOs in less than two years, and it recently changed its top sales, marketing, product development and engineering executives.

Under Liddell, GM posted four straight profitable quarters and began to repair accounting troubles that had plagued it for years. The former Microsoft CFO joined GM in January 2010 with a reputation as a problem solver.

At the time, Liddell said he was leaving Microsoft with an eye on taking a higher position. When former GM CEO Ed Whitacre stepped aside last year, GM picked board member Dan Akerson to replace him, leading to speculation that Liddell was unhappy about being passed over.

But Liddell denied that he was leaving because he didn't get the CEO job, saying he was solely focused on the public stock offering at the time Whitacre left.

"I didn't have any expectations other than that, and I didn't when I joined the company," he said.

Shares of GM fell 68 cents, or 2.1 per cent, to $31.57 in morning trading Thursday.

Akerson said Liddell was a major contributor to GM during a pivotal time in the company's history.

"He guided the company's IPO process and established a good financial foundation for the future," he said.

Liddell replaced Ray Young, who was transferred to GM's operations in China.

GM had been plagued with financial reporting problems heading into and emerging from bankruptcy protection. Going into its IPO last year, the company said weaknesses in its financial controls meant many of its numbers could not be considered reliable.

Steven Rattner, former head of the government's autos task force, has said that GM had the weakest finance operation that task force members had seen in a major company.

But just two weeks ago, when GM released its 2010 earnings, the company said those problems had been fixed.

GM reported net income of $4.7 billion last year, fueled by strong sales in China and the U.S. as the global auto market began to recover. It earned $2.89 per share on revenue of $135.6 billion. It was the company's best performance since earning $6 billion in 1999 during the height of the pickup truck and SUV sales boom.

GM accepted nearly $50 billion in government help to help it survive in 2009. But the company has since made an impressive recovery with global sales growing 12 per cent last year.

The company must still pay back more of its rescue aid. GM's owners, the U.S. Treasury Department, the Canadian (federal) and Ontario governments and a union health care trust fund, sold common stock in the November IPO. The U.S. government got $13.5 billion from the sale and will have to sell its remaining shares for $53 each to break even on its aid to GM.