MILAN—Stellantis made a fast start in its first year after the merger of Fiat Chrysler and Peugeot maker PSA, with the world’s No.4 carmaker reporting profitability and benefits from the combination both ahead of target. The group said on Wednesday the margin on its adjusted operating profit was 11.8 percent in 2021, above its target of around 10 percent, thanks to strong progress on synergies, which generated around 3.2 billion euros ($3.6 billion) in net cash benefits. The carmaker’s Milan-listed shares were up 5.7 percent at 10:40 a.m. GMT. “Record results prove that Stellantis is well-positioned to deliver strong performance, even in the most uncertain market environments,” Chief Executive Carlos Tavares said in a statement. Tavares will next week present the group’s detailed business plan. Stellantis guided for a double-digit margin again this year. The pro-forma figure for 2020 was 6.9 percent. Margins in North America climbed to a record …