ExxonMobil Corp. (NYSE: XOM) CEO Rex Tillerson, who is U.S. President-elect Donald Trump's pick for Secretary of State, would retire at the end of the year, the oil major said Dec. 14.

Darren Woods, president of ExxonMobil, would take over as chairman and CEO, effective Jan. 1.

With the retirement of Tillerson, the ExxonMobil board now is comprised of 12 directors, 11 of whom are non-employees.

Tillerson was scheduled to retire in March when he reached 65, the company’s mandatory retirement age for his position. After consideration, Tillerson concluded, and the board agreed, that given the significant requirements associated with the confirmation process as Secretary of State, it was appropriate to move the retirement date.

Tillerson joined Exxon Co. USA in 1975 as a production engineer. He held various senior roles in the corporation throughout his career spanning more than four decades, including executive vice president of ExxonMobil Development Co.

He was named senior vice president of ExxonMobil Corp. in 2001 and was elected president and member of the board of directors in 2004. Tillerson was elected chairman and CEO in January 2006.

Woods, 51, was elected president of ExxonMobil and a member of the board of directors in January 2016. He joined Exxon Co. International in 1992.

During his career, Woods held various senior domestic and international positions in ExxonMobil Refining & Supply Co., ExxonMobil Chemical Co. and Exxon Co. International. He also served as manager of ExxonMobil investor relations.

In 2012, he was appointed president of ExxonMobil Refining & Supply Co. and a vice president of the corporation. In this role, Woods had primary responsibility for the company’s global refining, supply and transportation activities. In 2014, he was named a senior vice president of the corporation and became a member of its management committee.

Woods earned a bachelor’s degree in electrical engineering from Texas A&M University and a master’s degree in business administration from Northwestern University’s Kellogg School of Management. He was born in Wichita, Kan.