Sergio Marchionne, the executive who pulled two ailing carmakers from the brink of collapse and led the improbable transformation of Fiat Chrysler into an automotive giant, died Wednesday in Zurich. He was 66.

John Elkann, the chairman and chief executive of Exor, the holding company controlled by the Agnelli family, which founded Fiat in 1899, announced the death in a statement.

Marchionne was incapacitated about three weeks ago by complications of shoulder surgery, which he underwent in Zurich July 5. He was reportedly later put on life support. After Fiat Chrysler announced he would be “unable to return to work,” the company appointed a successor last weekend.

“Unfortunately, what we feared has come to pass,” Elkann said Wednesday. “Sergio Marchionne, man and friend, is gone.”

Marchionne took over Fiat, in Turin, Italy, in 2004 and spearheaded the acquisition of Chrysler in 2009. The businesses were near collapse. He defied those gloomy predictions. Today, Fiat Chrysler Automobiles and Ferrari, which was spun off during Marchionne’s tenure, are worth nearly 10 times as much as they were when he took over.

An Italian-born Canadian, Marchionne had a reputation as a chain-smoking workaholic who forged his career as a tax consultant before moving to a metals-trading firm and a trade services company.

His legacy was defined by his work in the automotive industry. When he was hired by the Agnelli family to run the company, they charged him with reversing its long decline.

Acting quickly, he dismissed several executives, pared back production levels to meet demand and eliminated slow-selling models. Before long, Marchionne became closely watched as one of the fastest-moving chief executives in the auto industry.

He took advantage of an existing deal between General Motors and Fiat to attempt to force GM to buy the Italian carmaker. His hard bargain for Chrysler in 2009 may be what defined his career.

Marchionne offered to take control of Chrysler, the sickest of Detroit’s Big Three automakers, and provide cars and technology to revive it — but only if the company didn’t have to pay for Chrysler.

It was the beginning of a remarkable rescue in the auto industry. Today Fiat Chrysler, while still facing challenges, is profitable. He planned to retire next year before becoming critically ill.