DirecTV Group on Monday announced that Mitch Stern, president and CEO of DirecTV’s operations in the United States, is leaving the company, effective immediately.

A former News Corp. executive, Mr. Stern joined DirecTV in December 2003 after News Corp. acquired a controlling stake in the satellite operator, and he was a key player in the company’s stratospheric growth last year.

The company didn’t provide a reason for Mr. Stern’s departure. However, people familiar with the matter said that his cross-country commute-Mr. Stern lives in New York and was flying to DirecTV’s Los Angeles headquarters each week-was taking a toll on him and his family.

Mr. Stern was pivotal in shepherding the company’s subscriber growth at a time when the company was shedding noncore assets. Because the company has sold off many of those noncore businesses, there are no plans to replace Mr. Stern, the company said.