Tuesday's announcement that Chesapeake Energy CEO Aubrey McClendon would resign April 1 helped push the company's shares up 6 percent in trading Wednesday, but his successor will face challenges continuing its recovery.Chesapeake is still the nation's second-largest producer of natural gas, the same rank it holds in North Texas' Barnett Shale. At the same time it is starved for cash and burdened with $16 billion in long-term debt.McClendon's agreement to leave the company he helped found in 1989 capped a shareholder revolt by Carl Icahn and Southeastern Asset Management Inc.'s O. Mason Hawkins that last year had cost him the chairmanship he'd held for more than two decades. McClendon also relinquished his annual bonus and saw executive perks curtailed amid federal investigations of a portfolio of personal loans that topped $840 million.Chesapeake jumped more than 10 percent when markets opened before settling down to gain $1.14 to close at $20.11. More than 73 million shares traded hands, more than five times the usual volume. At that price, investors still value the Oklahoma City-based company at nearly $13 billion."Companies have life cycles, and during various stages it can make sense for some people to leave," Philip Weiss, an analyst at Argus Research Corp. in New York, said in a telephone interview. "Aubrey McClendon was very good at accumulating land but now that Chesapeake is moving into an asset-harvesting mode, they must have decided they needed someone with another set of skills."McClendon shed more than $10 billion worth of production and pipelines last year to raise the cash needed to operate. The next CEO faces the task of whether to raise another $8 billion from asset sales this year to plug a similar funding shortfall, or continue McClendon's goal of making an oil company out of the producer of enough gas to supply 20 percent of American household demand."The imminent departure of CEO McClendon proves that major strategy changes are likely, and we envision a reduced spending environment that is less reliant on asset sales," Tim Rezvan, an analyst at Sterne Agee & Leach Inc. in New York, who has a neutral rating on Chesapeake shares, wrote in a note to clients Wednesday.Judging by bond investors, the company solvency isn't in question. Chesapeake bonds due in 2019 are trading at 99.749 cents on the dollar, according to Trace, the bond-price reporting system of the Financial Industry Regulatory Authority.Archie Dunham, the former ConocoPhillips chief who replaced McClendon as chairman in June, in an e-mail to employees said the company isn't for sale. Chesapeake has a large Fort Worth unit with about 500 employees.Dunham and McClendon declined to be interviewed for this story, according to Michael Kehs, a Chesapeake spokesman.Icahn and Hawkins, who together control 22 percent of Chesapeake's stock, pushed for McClendon's resignation after concluding that his presence and the controversy surrounding his personal business deals were hurting the share price, a person with knowledge of the discussions said.