"It is with the deepest sadness that EXOR has learned of the passing of Sergio Marchionne," the holding company of the Italian auto giant that Marchionne steered for 14 years, said in a statement Wednesday.
Fiat Chrysler Automobiles (FCA) had announced at the weekend that Marchionne, 66, was gravely ill in hospital in Zurich. He had suffered serious complications after surgery on his right shoulder last month.
EXOR's chief executive John Elkann said: "Unfortunately, what we feared has come to pass. Sergio Marchionne, man and friend, is gone."
The Italian-Canadian executive took the reins at Fiat in 2004.
Marchionne is credited with revamping the company, Italy's premier private enterprise, from top to bottom.
In 2009, he merged Fiat with US automaker Chrysler, then hived off its industrial vehicles unit in 2011 to create CNH Industrial and successfully spun off the luxury brand Ferrari in January 2016.
In a 2016 interview, Marchionne is quoted as saying: "If you put a Ferrari sticker on a toaster it doesn't go any faster. And just to celebrate this they gave me a red toaster with a Ferrari logo on it, just to remind me of that fact."
Ferrari's Sebastian Vettel may be wishing he could just put a Ferrari sticker on his car and make his driving woes go away.
He is still reeling from his crash defeat in Sunday's German Grand Prix, despite leading, handing the championship advantage to rival Lewis Hamilton.
The forecast looks equally bleak for Fiat Chrysler. Its shares tumbled almost 10% at the start of trading in New York early on Wednesday, after the firm cut its profit and revenue forecasts for this year.
The plunge in Fiat Chrysler’s share price can’t be directly attributed to Marchionne’s death, as his long stint as CEO ended last weekend.
However, the slump in FCA's shares is a stark reminder to the markets that the auto sector is a tough place for new CEO Mike Manley to navigate.