Talos Energy said on Friday its CEO Tim Duncan had stepped down on Aug. 29 after serving more than 12 years as the U.S. oil and gas firm's top boss.
Shares of the company fell 2.7% in premarket trade.
The company named board member Joseph Mills, who has more than four decades of experience in the oil and gas industry, as its interim chief.
Talos did not immediately respond to Reuters' questions about Duncan's departure.
Duncan had joined Talos as its chief executive in January 2012 and also serves as board member at natural gas producer Chesapeake Energy, according to his LinkedIn profile.
Under Duncan, Talos had been part of a handful of companies to have made significant discoveries in oil and gas exploration areas in offshore Mexico.
Talos said its board has initiated a search for a successor in partnership with a leading executive search firm.
(Reuters - Reporting by Sourasis Bose; Editing by Krishna Chandra Eluri)