Shares of Chesapeake Energy moved up more than 5 percent today after the company announced Tuesday that embattled co-founder and CEO Aubrey McClendon will retire April 1 in the wake of a board review into his personal finances and use of corporate assets.McClendon, 53, who helped start Chesapeake in 1989 and was stripped of the chairman's title last year, will continue serving as CEO until a successor is appointed, the Oklahoma City-based company said Tuesday.Chesapeake shares (ticker: CHK) were up $1.02 to $19.99 in mid-morning trading after surging as much as 10 percent after hours on Tuesday. The company's stock had reached nearly $70 in mid-2008 before collapsing to a low of $11.32 later that year and struggling to recover. The company said its investigation into McClendon's borrowings to pay for stakes in Chesapeake wells "to date has not revealed improper conduct." McClendon was granted the right to participate in company wells if he paid his share of costs, but he financed it by borrowing from companies that also loaned money to Chesapeake, a possible conflict.Chesapeake said it will release the results of that review Feb. 21, the same day it announces 2012 earnings.In a prepared statement, McClendon cited "certain philosophical differences with the new board," but said he would work for a smooth leadership transition. "I am confident that Chesapeake is in a great position to continue to grow and achieve great success in the future as it realizes the full value of its outstanding assets."It is the billions of dollars that Chesapeake spent to accumulate those assets, including more than 2,500 wells in the Barnett Shale in North Texas, that are at the heart of the company's current difficulties. A landman by training, McClendon plunged aggressively into new shale gas fields from Texas to Pennsylvania to wrap up leases before competitors.Chesapeake discovered the Haynesville Shale in Texas and Louisiana and drove a leasing frenzy in the Barnett Shale that pushed signing bonuses to unheard-of levels. It remains the second-largest natural gas producer in the Barnett Shale as well as nationally.But the boom went bust after natural gas prices began a long slide after peaking at more than $13 per 1,000 cubic feet in July 2008. Last spring, prices bottomed out at less than $2 as the supply of shale gas ballooned. Chesapeake had to trim jobs and capital spending while also selling off more than $30 billion in production and pipelines since 2008, including more than $10 billion last year.It has also put up for sale its downtown Fort Worth office tower, Chesapeake Plaza, formerly the Pier 1 Imports building, where it has a large operations center. Its Barnett Shale employment has fallen to about 500 as it sold assets and trimmed its drilling fleet from dozens in past years to just two.The company lost $1.07 billion during the first nine months last year even as its long-term debt swelled to $16 billion.McClendon's woes crested last year following news reports of his borrowings for the wells. The Internal Revenue Service and U.S. Securities and Exchange Commission began probes, and the furor culminated in May when the board announced it would remove him as chairman.He received a stinging rebuke in June at the company's annual shareholders meeting when two existing directors received barely a quarter of the votes cast and new board members nominated by two big investors gained a majority.Former ConocoPhillips Chairman Archie Dunham was named to lead the reconstituted board.Tuesday, Dunham said the company "is at an important transition in its history, and Aubrey and the board of directors have agreed that the time has come for the company to select a new leader." He said budgets and operations decisions "will be made with the goal of prudently growing the company's intrinsic value per share for the long-term benefit of its shareholders."Chesapeake plans to halt McClendon's well-investment program next year, rather than the original termination date at the end of 2015. The company reported earlier this year that as of the end of 2011, McClendon owed $846 million on loans taken out to finance as much as a 2.5 percent stake in company wells.Chesapeake's announcement said McClendon will receive "full compensation and other benefits to which he is entitled" and "will continue to be an important partner with the company given his stock ownership as well as his interests in certain of the company's wells. McClendon owns about 3 million shares of company stock, according to a Jan. 4 filing.The report contains material from Bloomberg News.