Chesapeake Energy Corp., the U.S. natural-gas producer criticized for allowing its top executive to invest in the company's wells, prohibits other senior managers from the same practice.

Executives who oversee finance, operations and acquisitions for Oklahoma City-based Chesapeake have employment contracts that bar them from any investment or involvement in the oil and gas industry outside of their duties for the company, a review of Securities and Exchange Commission filings showed.

Chairman and Chief Executive Officer Aubrey McClendon has been borrowing hundreds of millions of dollars annually — some from Chesapeake's financiers — to participate in a perk reserved only for the CEO that allows him to buy stakes in company-owned wells. After defending the well-ownership policy last week, directors yesterday said they will halt the program and review McClendon's loans. Chesapeake shares have fallen 25 percent this month.