Boeing CEO Dennis Muilenburg is the latest casualty in a string of chief executive exits this year.
Through November, 1,480 CEOs left their companies in 2019, according to business and executive coaching firm Challenger, Gray & Christmas. That's the highest number on record for the first 11 months of a year.
December has brought other high-profile resignations including the chief executives of United Airlines, Alphabet, Expedia, SoulCycle and Away, which would make 2019 the highest year on record for executive departures.
Andy Challenger, vice president of Challenger, Gray & Christmas, said there is not one simple reason for why so many departures have happened this year, but he would tie it to the U.S. being in its longest economic expansion in history.
"Part of being in a great economy is that it's an easy time to make transitions," Challenger said. "People are getting packages that are more favorable, when stocks are at an all-time high."
The previous highest total year on record was 2008, when 1,484 chief executives departed in the midst of the financial crisis. The firm started tracking CEO departures in 2002.
The vast majority of CEO departures this year were from private companies or the government sector. Only 284 of those exits through November were from publicly traded companies.
Muilenburg joins their ranks as Boeing battles scrutiny after two fatal crashes of its bestselling plane, the 737 Max. The company announced the leadership change on Monday. Boeing Chairman David Calhoun will replace Muilenburg as CEO of the embattled manufacturer on Jan. 13. CFO Greg Smith will serve as the interim chief executive until then.
Notably, Boeing is maintaining its decision to keep its chairman and CEO positions under the control of two separate individuals.
Up until October, Muilenburg had been both CEO and chairman. But when the Boeing board removed the chairman title from Muilenberg, saying it would help him focus on the 737 Max crisis, it named longtime board member Calhoun as non-executive chairman. As Calhoun steps into the CEO position, he will hand over the chairman title to board member Lawrence Kellner.
Some corporate governance experts have advocated that companies should split the CEO and chairman roles in order to have better oversight. While Boeing's situation with the 737 Max is unique, in the wave of CEO changes this year, more and more companies are shifting to this structure.
In 2005, 30% of chairman and CEO roles at companies in the S&P 500 were split, according to Institutional Shareholder Services, a proxy advisory firm. As of early November, that has increased to 53% this year.