Sergio Marchionne, longtime CEO and chief for Fiat Chrysler Automobiles, stepped down Saturday due to serious complications after surgery, the company announced. Mike Manley, head of Jeep and Ram brands, replaced him. 

John Elkann, grandson of Gianni Agnelli and chairman of the company that controls FCA, said his family was shocked by Marchionne's failing health.

"I am profoundly saddened to learn of Sergio’s state of health. It is a situation that was unthinkable until a few hours ago, and one that leaves us all with a real sense of injustice," Elkann said in a statement.

Elkann will fill Marchionne's chairman role at Ferrari while the Italian firm is expected to name Louis C. Camilleri as the replacement for Machionne's CEO role.

Marchionne, who is 66 years old, recently underwent surgery on his right shoulder and was expected to miss the company's second-quarter sales call due to the procedure. It's unclear if his sudden departure is related to the surgery or complications after the surgery. The Wall Street Journal  report Satuday that Marchionne had been absent from day-to-day activities at FCA for weeks.

Marchionne was expected to step down from his role as CEO next year, although it was unclear who would lead the company after his exit.

Manley joined the automaker in 2000 and has led Jeep for nearly a decade. His roles have included head of sales in Asia, head of Ram brand, and chief operating officer for North America.

Marchionne helped navigate FCA through bankruptcy during his 14-year tenure and turn the company's finances back from the brink of collapse. As CEO, Marchionne has led FCA through multiple plans for profitability, which the automaker has largely delivered on, and spun off Ferrari as a successful standalone business unit. Marchionne also served as CEO for Ferrari.

Last month, FCA paid off its net industrial debt, which was part of a larger plan to spend billions on new cars and technologies by 2022.

Marchionne's tenure also has been controversial at times. He openly courted partners such as General Motors and other automakers, and said consolidation was the only way that the auto industry could survive. His efforts to revive Alfa Romeo and Maserati as luxury brands in the U.S. have largely stalled, and the plainspoken CEO has also questioned whether electrification and self-driving cars could be profitable.