Brian Duperreault, 70, can’t seem to stay retired.

Mr. Duperreault, who was named the new president and CEO of American International Group Inc. last month, made that clear during the Chairman’s Chat at Insure-Tech Connect 2016 in October when he discussed how he came out of retirement to take over at Hamilton Insurance Group Ltd.

“I’ve retired a couple of times,” he said. “I’m actually good at retiring. I’m just not good at staying retired. I felt like I still had some gas in the tank.”

The tank apparently still hasn’t reached “E” yet, as Mr. Duperreault, a longtime insurance executive who worked at AIG in the 1970s and 1980s, now occupies the top spot at the New York-based insurer.

“He came up the ranks of AIG when it was a proud franchise so it’s a happy opportunity to be the one to put it back on solid footing,” said Brett Horn, senior equity analyst at Morningstar Inc. in Chicago. “I think his background fits exactly what is still the main problem at AIG, which is getting commercial underwriting back in line with peers.”

Mr. Duperreault spent more than 20 years at AIG, rising to lead American International Underwriters, which comprised the insurer’s overseas operations. In 1994, he left to head Bermuda-based Ace Ltd. and transformed it into a multinational insurer.

He retired from Ace in 2006 but came out of retirement in 2008 to lead Marsh & McLennan Cos. Inc. and help turn around the brokerage, which was still recovering from the reputational crisis triggered by the broker commission and bid-rigging investigations of then-New York Attorney General Eliot Spitzer. He retired from Marsh & McLennan at the end of 2012. Less than a year later, he came out of retirement again to lead Hamilton.

How long he will remain at AIG this time around is anybody’s guess, though.

Mr. Duperreault will “have to deal with succession issues sooner than later,” said Paul Newsome, Chicago-based managing director of equity research at Sandler O’Neill & Partners L.P.

“It’s hard to imagine — though it’s possible — that he would run the company for the next decade,” he said.

Gloria Vogel, an adjunct finance professor at New York University and insurance industry analyst, said industry observers expect Mr. Duperreault to stay on at AIG for “three to five years, make the improvements-much like he did with Marsh, train a successor, and then retire for the third or fourth time.”