Swift Transportation Company announced the retirement of founder and CEO Jerry Moyes, effective Dec. 31, 2016.

He'll be replaced by Richard Stocking, who has been president and chief operating officer of the Phoenix-based company since 2010. During the transition period, Moyes and Stocking will serve as co-CEOs, but daily responsibilities will be transitioned to Stocking immediately.

Moyes, who started the business in 1966 with a single truck, was one of the last of a group of trucking leaders who led the rise of the truckload industry after trucking was deregulated in 1980. 

However, as the Wall Street Journal reports, in the past year, the 72-year-old executive has come under fire for pledging Swift shares as collateral for personal loans.

“I want to thank everyone at Swift for helping me build this great company over the last 50 years,” said Moyes. “I am proud of all of Swift’s employees who drive the performance of this company, and I am confident that Swift will continue on its successful path.”

As of Jan. 1, Moyes will serve as founder and chairman emeritus and a member of the board of directors.

Stocking has been with Swift since 1992 with experience managing all facets of the business including operations, sales, marketing, safety and recruiting. He served in other leadership capacities including executive vice president of sales and regional vice president of operations.

“Beginning 50 years ago, hauling steel with a single truck, Jerry Moyes created a strong, enduring company and built Swift into one of the largest truckload providers in the U.S.,” said Richard Dozer, chairman of the board of directors. “We are deeply grateful to Jerry for his innumerable contributions to Swift’s growth and success. We wish Jerry all the best in his well-deserved retirement and look forward to his continued guidance and experience on the Board.”

Swift is based in Phoenix, Ariz., and operates a fleet of 18,000 units with company and owner-operator drivers. The company has more than 40 terminals in the U.S. and Mexico.