But on Saturday it said Marchionne had experienced "unexpected complications" during his recovery and that the problems had "worsened significantly in recent hours".
The announcement after an emergency board meeting Saturday marked the end of the Marchionne era, which included the turnaround of failing Fiat, the takeover of bankrupt USA automaker Chrysler and the spinoffs of the heavy machinery and truck maker CNH and supercar maker Ferrari.
Financial investors sent shares in Fiat Chrysler tumbling 4 per cent on Monday as they weighed the potential impact of the accelerated exit of CEO Sergio Marchionne due to serious health issues. Some of the debt carried at 12 percent interest rate and cost the company $1.2 billion in interest per year.
Marchionne had been due to step down next April as head of the world's seventh largest carmaker, so the market reaction to his sudden departure was relatively limited.
Marchionne, then serving as CEO of goods inspector SGS SA, is appointed CEO of Fiat. Both brands have formed the leading edge of FCA's North American strategy to move away from passenger auto production and focus on SUVs and trucks to meet market demand.
"It was a situation that was unthinkable until a few hours ago, and leaves us all with a sense of injustice", he added. "My first thoughts go to Sergio and his family", Elkann said. Meetings took place in Turin on Friday to choose his successor, sources said. He won control of Chrysler in a 2009 deal with U.S. President Barack Obama's government without putting a penny down, only in exchange for bringing more small-car technology to Chrysler.
Ferrari board member Louis Camilleri is the new chief executive of the brand, a role he will fulfil in parallel with a position as chairman of Phillip Morris, parent company to the Marlboro tobacco brand.
As the company prepares to pass the CEO job to Jeep executive Mike Manley, here is a timeline of some key moments during Marchionne's tenure.
Candice Miller, Macomb County public works commissioner and former Republican congresswoman from Harrison Township, said she is sorry to hear Marchionne is stepping down. 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.
Jeep executive Mike Manley, who replaces the ailing Sergio Marchionne as the head of Fiat Chrysler Automobile, had been one of Marchionne's closest collaborators at the group.
Most notably, he pushed for the Fiat-Chrysler merger despite those who said the Italian and American brands would never work as a combined company.
FCA said British-born Manley would pursue the strategy that Marchionne outlined last month.
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