BNSF Railway Co. said Matt Rose, once seen as a possible candidate to replace Warren Buffett as head of Berkshire Hathaway Inc., will retire from the railroad.

Rose, 59, who previously served as chief executive officer of BNSF, will step down as executive chairman in April 2019, the Fort Worth, Texas-based company said Wednesday in a statement. The company won’t fill the executive chairman position for now and Carl Ice, the current CEO, will be the top executive at the railroad, according to spokesman Zak Andersen.

Rose worked as CEO of BNSF for 13 years and helped sell the railroad to Berkshire in 2010, in one of Buffett’s largest deals at the time. The purchase expanded Buffett’s conglomerate and gave it another capital-intensive business where Berkshire Hathaway could put money to work. Buffett, 88, has praised Rose’s leadership, saying in his shareholder letter in 2014 that Rose was among Berkshire’s “extraordinary managers who have my gratitude.”

“Under Matt’s management, BNSF has become a major source of profit and pride” for Berkshire Hathaway, Buffett said in the statement. “It was a very lucky day for me and for Berkshire Hathaway when I met Matt Rose.”

Buffett’s oft-repeated praise of Rose sparked speculation that he could be among the potential candidates to replace Buffett as CEO of Berkshire one day. Earlier this year, Buffett named Ajit Jain, who leads Berkshire’s insurance businesses, and Greg Abel, who used to run the energy operations, to Berkshire’s board in a movement toward succession. Rose wasn’t elevated.

“Berkshire chief executives rarely retire early. But Rose’s departure is, ironically, a testimony to the company’s deep bench,” Lawrence Cunningham, a professor at George Washington University and author of the book Berkshire Beyond Buffett, said in an email.

Rose became BNSF’s executive chairman in 2013, when Ice was promoted to CEO. Rose helped the railroad navigate a decline in coal carloads, which weighed on North American railroads.

Berkshire’s railroad, which operates 32,500 miles of track in the Western U.S., has bet more on taking freight from trucks by hauling containerized cargo that carries merchandise such as toys and electronics. The company, for example, entered into an agreement with CSX Corp., which operates in the eastern U.S., to provide a premium service beginning this month that takes containerized freight from Los Angeles to Ohio.

Rising Efficiency

Since the acquisition in 2010, BNSF’s annual revenues climbed 27 percent to $21.4 billion in 2017 while initiatives under Rose to make the railroad more efficient helped operating profit to jump 63 percent to $7.3 billion. BNSF took steps in recent years to help overcome service delays that had plagued the railroad’s operations.

As executive chairman, he helped BNSF evaluate potential acquisitions and spent time in Washington to talk about industry-wide pushes, such as safety standards for tank cars that haul oil and other petroleum products.

“Through my 26 years at BNSF—19 in leadership—I have seen enormous change in our economy,” Rose said in the statement. “Our company has navigated those changes well and now is extremely well positioned for the next several decades.”