The newly merged company's stock, traded under the symbol FCAU, opened at $9 and rose quickly to $9.55 before falling to $8.91, or 1 percent in morning trading.
The company began trading in New York to raise its profile and give U.S. investors a chance to own part of the Chrysler comeback story. The stock will also trade in Milan, Italy.
"FCA's listing marks the hard-won arrival at a destination," Sergio Marchionne, CEO of both companies, said in a statement in New York, where he and Chairman John Elkann are scheduled to ring the closing bell at the NYSE to commemorate the first day of trading. "Today marks the beginning of our journey as one global automaker, one FCA," the statement said.
Chrysler is now profitable, driven by a rebound in U.S. sales, five years after a trip through bankruptcy and a takeover by Fiat orchestrated by the U.S. government. But that performance is offset by Fiat's struggles in Europe. Fiat Chrysler is the seventh-largest auto company in the world, and Marchionne wanted the merger to consolidate costs and technology to compete with larger global automakers.
Fiat Chrysler has an ambitious goal to grow sales 60 percent to more than 7 million cars and trucks by 2018. Combined, the companies sold 4.4 million cars and trucks last year, compared with 6.3 million for Detroit rival Ford. Toyota was the global leader with sales of 9.98 million vehicles.
Only a limited number of shares will go on sale Monday, mainly from Italian stockholders. The company is likely to sell about 85 million shares it now holds later in the year, after Marchionne and Chrysler Chief Financial Officer Richard Palmer do a "road show" explaining plans for the merged automaker. Additional shares or bonds that convert to stock also could be offered.
In an interview, Morningstar senior analyst Richard Hilgert said Fiat Chrysler faces macroeconomic troubles in Europe and South America, its two largest markets outside the U.S. Also, earnings likely will look smaller as the company switches from international to U.S. accounting standards, he said.
"Fiat Chrysler's stock is not for the faint of heart," said in a note to investors.
The stock's debut in New York comes at an inopportune time. The market, and auto stocks in particular, had a tough week, with both General Motors Co. and Ford Motor Co. shares hitting 52-week lows.
The combined company is counting on expanding sales at Jeep, Alfa-Romeo and Maserati and a revival of the Chrysler brand to place it firmly in the top ranks of global automakers.
Fiat owned 58.5 percent of Chrysler last year, and the two companies were combined in January when it bought the rest from a trust fund that pays health care bills for union retirees.
Marchionne, 62, who has led Chrysler's restructuring and combination with Fiat, said last week that he plans to stay with the company through 2018.