Shares in Stellantis rose as much as 7.5% on their first trading day, after the world's fourth largest carmaker was created with the completion of the $48 billion merger between Fiat Chrysler and Peugeot maker PSA. 

"We have the scale, the resources, the diversity and the knowhow to successfully capture the opportunities of this new era in transportation," Chairman John Elkann said in a video on the Borsa Italiana website. 

Chief executive Carlos Tavares said the merger would add €25 billion in value for shareholders over the years, thanks to projected cost cuts. 

"I can tell you that the focus from day one will be on the value creation that is the result of the implementation of those synergies," Tavares said in the same video. 

Fiat Chrysler (FCA) and PSA have said Stellantis can cut costs by more than €5 billion a year without plant closures. 

Milan-listed shares of Stellantis started trading at €12.758 and rose by 7.5% to stand at €13.51 in morning trade. The Paris-listed shares traded around the same level. 

That compares with Fiat Chrysler's (FCA) close on Friday at €12.57. 

Over the weekend, PSA shares were exchanged into new FCA shares. All FCA shares were then renamed as Stellantis. 

The stock will debut in New York tomorrow, when Tavares will also hold its first press conference as the head of Stellantis. 

Stellantis has deep enough pockets to fund the shift to electric driving and take on bigger rivals Toyota and Volkswagen.  

It took over a year for the Italian-American and French automakers to finalise the $52 billion deal, during which the global economy was upended by the Covid-19 pandemic. 

They first announced plans to merge in October 2019, to create a group with annual sales of around 8.1 million vehicles.

"The merger between Peugeot and Fiat Chrysler Automobiles that will lead the path to the creation of Stellantis became effective," the two automakers said in a statement. 

Analysts and investors are now turning their focus to how Tavares plans to address the huge challenges facing the group - from excess production capacity to a woeful performance in China. 

Like all global automakers, Stellantis needs to invest billions in the years ahead to transform its vehicle range for the electric era. 

But other pressing tasks loom, including reviving the group's lagging fortunes in China, rationalising its huge global empire and addressing massive overcapacity. 

FCA CEO Mike Manley - who will head Stellantis' key North American operations - has said 40% of the carmaker's expected synergies would come from convergence of platforms and powertrains and from optimising R&D investments, 35% from savings on purchases.

Another 7% will come from savings on sales operations and general expenses, he added.