Chris Liddell, who joined General Motors Co. as CFO 14 months ago and steered it through the largest initial public stock offering in Wall Street history, is leaving the automaker April 1.

Liddell, 52, who came to GM from Microsoft Corp., will be succeeded by Dan Ammann, 38, GM's treasurer. Ammann, who, like Liddell, is a New Zealand native, played a hands-on role in GM's IPO, reported Automotive News.

Liddell had been viewed as a possible successor to GM CEO Dan Akerson, 62. When Liddell arrived at GM in late 2009, many viewed him as a well regarded outsider who eventually would replace then-CEO Ed Whitacre. But GM's board chose Akerson for the top job last summer when Whitacre left.

During a conference call with reporters, Liddell said he wasn't stepping down because he was passed over. But he acknowledged that he's ready for a change from his position as CFO, which was the job he had at Microsoft and at International Paper Co. before that.

"I think my CFO days might be behind me as of the first of April," when he'll leave after a three-week transition, Liddell said. He said he doesn't have any firm plans.

Liddell said he had been "anguishing" over the decision for a few weeks and discussed it with Akerson over the past week.

"With the transition from Ed to Dan, which I think went incredibly well, my real focus at that stage was getting the IPO done," Liddell said. "I didn't have any other expectations other than that, and didn't when I joined the company."

More exec turnover

His surprise decision to step down follows a string of recent management changes atop GM.

In January, product czar Tom Stephens was moved to the job of global chief technology officer and was replaced by human resources executive Mary Barra.

Jamie Hresko, GM's global powertrain chief, left last week. And the marketing department has had multiple shakeups, including the December elevation of Joel Ewanick to global marketing chief.

During the conference call, Akerson downplayed the management turnover.

"We have tried to reconfigure the focus of the company," he said. "The two-pronged thrust here is marketing" and technology, Akerson said, especially the advancement of propulsion innovations.

Akerson said the appointments of Stephens and Ewanick were keys to sharpening that focus.

"I've kind of got the best of both worlds in those two fellows," Akerson said. "And Mary Barra is one of our most talented executives, and we've got her properly positioned."

He said Liddell "has been instrumental in establishing a good financial foundation for the company's future."

"He was a catalyst for change," Akerson said. "He helped simplify our business, strengthen our balance sheet."

In addition to executing the IPO, GM has posted four quarters of profits, strengthened its balance sheet, reduced debt and improved its financial reporting process.

Ammann's background

Ammann joined GM in March 2010 as vice president for finance and treasurer after a six-year stint as managing director and head of industrial investment banking at Morgan Stanley.

Akerson said Ammann "played a major role in the financial decisions over the last year," including the reduction of GM's debt load as well as in the IPO.

"We were very fortunate to have such a strong candidate internally," Akerson said. "We expect this will be a seamless transition."

Ammann leads the GM Treasurer's Office in New York City. Prior to his stint at Morgan Stanley, Ammann spent five years at Credit Suisse in New York and New Zealand.

"Chris and I have worked together really very closely on the financial strategy of the company over the last year," Ammann said. "What you'll see going forward is absolutely more of the same."

Wall Street reaction

In a note to investors, Morgan Stanley analyst Adam Jonas said Liddell's departure could "re-ignite concerns about potential instability in GM's management ranks."

He also noted the bad timing of the move, coming just after GM's first full quarter as a public company and "at a time of heightened geopolitical and macroeconomic risk."

Still, Jonas said that he has a "positive impression" of Ammann, and that he doesn't think Liddell's departure changes GM's profit outlook.

Barclays Capital analyst Brian Johnson, in a note to investors, wrote: "While the old GM culture needed to be fixed, the recent high turnover indicates that the new GM management team is still integrating." He noted GM now is on its fourth CEO and fourth CFO in two years.

GM shares fell 82 cents, or 2.6 percent, to close at $31.42 a share on the day amid a broad market downturn. The Dow Jones industrial average plunged 228 points to close at 11,985.