Chesapeake Energy Corp. (NYSE: CHK) said on Sept. 27 that two board directors including a representative of activist investor Carl Icahn resigned on Sept. 26, one week after Icahn cut his stake in the natural gas producer by more than half.

Chesapeake said the resignations were not due to any disagreement, but did not specify why the two directors stepped down.

John Lipinski, who has been on Chesapeake's board since June 2014, and Vincent Intrieri stepped down on Sept. 26, the company said. Intrieri, who has served as senior managing director of Icahn Capital LP, was on Chesapeake's board since June 2012 when Icahn asked to replace at least four directors and revealed a stake in the company.

Icahn said during the week of Sept. 19 that Chesapeake's management had done "an admirable job" over the last few years and that he reduced his stake in the company by 51.6% to 4.55% for tax planning purposes.

In 2012 Chesapeake appointed four new independent directors, three proposed by Southeastern Asset Management, its largest shareholder then, and one proposed by Icahn, who was its second-largest shareholder at the time.