Hess Corp., a U.S. company focused on exploration and production, said a former boss at Deloitte was taking charge with chairman Mark Williams standing down.

Hess said Chairman of the Board of Directors Williams was retiring immediately because of health reasons. James Quigley, who once led accounting and consulting firm Deloitte, is taking over. Before serving with Deloitte, he was a trustee at an oversight body of the International Accounting Standards Board.

"It has been a privilege and pleasure to work with Mark, as we have taken important steps together to preserve our financial strength and build our portfolio of high quality assets, especially in the current oil price environment," Quigley and CEO John Hess said in a joint statement.

Hess has been focused on transitioning to exploration and production in the United States after selling its entire retail sector of gasoline stations and convenience stores to Marathon Petroleum Corp. in 2014.

A decline in crude oil prices, off about 40 percent from last year and 70 percent below mid-2014 levels, has put significant pressure on companies like Hess as capital for exploration and production evaporates.

Hess took a net loss of $396 million for the fourth quarter against $53 million in income year-on-year. Most of the company's loss during the fourth quarter came from its upstream, or exploration and production, portfolio.

In a separate statement, the company said it declared a regular quarterly dividend of 25 cents per share payable to common shareholders.