By Jeff Raymond, Oklahoma Impact Team

OKLAHOMA CITY - Billionaire investor Carl Icahn has purchased 7.56 percent of Chesapeake Energy stock and blasted the board of directors, demanding they be replaced.

Icahn, who held a large number of Chesapeake shares in 2010, upped his stake to almost 50.1 million shares, corporate filings show. This increase in stock ownership and an accompanying letter to the filings show that Icahn intends to take a more active role in the company's affairs.

In the letter, Icahn explains that a corporate board's responsibilities are to hold management accountable and ensure stability for shareholders.

"We believe the board has failed this duty in a dramatic fashion," Icahn wrote. "Rather than act as a source of stability and provide assurance to shareholders, this board has led the company through a highly publicized spate of corporate governance breakdowns while amassing an astounding $16 billion funding gap, which we believe has contributed to the share price decline of over 55 percent from the 52-week high."

The letter notes the shareholder lawsuits that have been filed since news broke that Chesapeake CEO Aubrey McClendon borrowed more than $1 billion, using his stake in company wells through the company's unique Founder Well Participation Program as collateral.

"Between the ‘constant stream of negative news' and the ‘half hearted attempt by the board to make the minimum possible number of changes,' Chesapeake must deal with its fiscal and credibility problems," Icahn wrote.

In the letter, Icahn says he suggested to McClendon that Chesapeake consider having direct shareholder representation on the board, something the company refused to consider until after a replacement board chair is chosen. The board removed McClendon as board chair in April, pending selection of a replacement.

"We believe that this response was completely disingenuous and illogical," Icahn wrote. "Why is appointing a new chairman, sometime out in the future, an excuse for putting off considering whether to have shareholders, the true owners of the company, have immediate representation on this very flawed board in this very fluid situation?"

Allowing the current board to select a new chairman in the absence of shareholder approval and representation "is akin to asking the fox, who has plundered the hen house, to choose another fox to assist it in standing guard over the remaining hens," he wrote.

Icahn proposed that four of the current directors be pushed aside in favor of two he would designate and two designated by another large shareholder, such as Southeastern Asset Management, the company's largest shareholder. Corporate filings show that Southeastern Asset Management also increased its stake in Chesapeake this week.

Icahn cited the company's spending and problems with board representation as reasons he sold his previous Chesapeake shares.

Icahn concludes the letter by pledging to take any actions necessary "to protect the value of this company" should Chesapeake ignore its demands.