In 1997 he was hired at Marathon Oil, then a subsidiary of U.S. Steel, as the senior vice president for finance & accounting. In 1998, he became president of Speedway SuperAmerica, a subsidiary of Marathon, and in 2001 he became president of Marathon Ashland Petroleum, another subsidiary. When U. S. Steel and Marathon separated at the end of 2001, he stayed with U. S. Steel as vice chairman and chief financial officer. He became president of U. S. Steel in March 2003, and chairman of the board as of February 2006.