Exxon Mobil Chairman and CEO Lee Raymond will retire at the end of the year.

NEW YORK (CNN/Money) - Exxon Mobil Corp. said Thursday Chairman and CEO Lee Raymond will retire at the end of the year and that the board is expected to elect company president Rex Tillerson as his successor.

Raymond, 66, has served the company for more than 42 years, including over 21 years as a director, the company said in a statement.

After reporting more than $25 billion in annual profit last year, under Raymond's reign Exxon (down $0.22 to $58.78, Research) recently stole the mantle of the world's most valuable company from General Electric Co. (down $0.16 to $34.05, Research) As of Thursday, Exxon was worth $376 billion, ahead of General Electric Co. at $361 billion.

"Lee Raymond really set the standard for other CEOs in the industry," Oppenheimer & Co. analyst Fadel Gheit told Reuters. "Everybody else copied Lee Raymond, but you can't duplicate what he's done."

Prior to the merger of Exxon and Mobil in, 1999, Raymond was chairman and CEO of Exxon, the company said.

Until now, Exxon had remained silent on when Raymond would leave. Asked about his future plans at the Reuters Energy Summit in June, Raymond told Reuters, "You either retire or die and I'd just as soon not die."

Raymond has watched several bouts of frenzied oil prices and subsequent collapses, presided over one of the few successful mega-mergers in corporate history and helped make Exxon one of the most consistently profitable companies in the world.

"He did a tremendous job at Exxon Mobil, making the Mobil acquisition when oil was $10 a barrel as opposed to all these other executives now making all their acquisitions when oil is at $55," Craig Hodges, fund manager at Hodges Capital Management, which owns Exxon Mobil shares, told Reuters.

Hailed within corporate America for his disciplined approach to running a company whose operations span nearly 200 countries, Raymond was hated by many environmentalists for his stance on global warming and Exxon's role in the Valdez disaster in Alaska.

The company and Raymond would not comment to Reuters beyond what was included in Thursday's press release. The statement said only that the change in leadership, "is consistent with the board of director's succession plan developed years in advance and further demonstrates the strength of the management development system."

Exxon (down $0.22 to $58.78, Research) shares edged lower in afternoon New York Stock Exchange trading.

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For more on Raymond's legacy, click here.

Nokia's CEO Jorma Ollila is also leaving. Click here to find out who will take his place.

Click here to find out what he's doing with Shell.

-- from staff and wire reports