AIG is bringing Sierra Signorelli back to the company to lead its commercial insurance businesses across the Americas, putting a former global chief underwriting officer in charge as conditions diverge sharply between some of the US market’s largest lines.
Signorelli will become chief executive officer of Americas and Global Personal Insurance on January 1, 2027. Reporting to CEO Eric Andersen, she will oversee AIG’s North America and Latin America & Caribbean Commercial Insurance businesses, as well as Global Personal Insurance.
The breadth of the role puts Signorelli over businesses facing very different underwriting conditions. Commercial P&C premiums across the US fell an average 2% in the second quarter, according to the Council of Insurance Agents & Brokers’ latest market survey, but the headline figure masks a growing split. Property premiums fell 6.3% as capacity expanded, while umbrella and commercial auto increased 5.3% and 4.5%, respectively.
That divergence is giving intermediaries more options in some placements while leaving others difficult to negotiate. Greater property capacity has already created more competition for commercial accounts, even as casualty remains considerably firmer.
AIG’s own book reflects some of that contrast. North America Commercial net premiums written rose 9% to $3.1 billion in the second quarter, driven by retail casualty and financial lines and partly offset by lower business at Lexington, primarily in property. The unit produced an 84.0% combined ratio, compared with 85.9% a year earlier, according to AIG’s second-quarter results.
Signorelli arrives with experience on both the underwriting and operating sides of large commercial insurance businesses. She rejoins AIG from Zurich, where she has held roles including CEO U.S., CEO Commercial Insurance and group chief underwriting officer, and has served on the group’s executive committee since 2021.
Before joining Zurich in 2017, she spent 17 years at AIG in its Global Specialties division, including as global chief underwriting officer for specialty lines. Zurich named Alex Wells to succeed Signorelli as its US chief executive earlier this month, with Wells moving up from leadership of its middle-market, programs, captives and direct-markets businesses. Zurich US named Wells CEO following Signorelli’s departure.
“Sierra is a highly respected global insurance executive with significant relationships across the industry,” Andersen said.
The appointment also adds another underwriting-focused executive to a leadership structure that has been changing under Andersen. AIG created a dedicated global client and broker relationships role earlier this year, appointing former Aon US co-head Christine Williams to oversee relationships across the company. Williams joined AIG in September.
Signorelli’s arrival therefore comes as AIG is building out both the underwriting and distribution sides of its senior team while navigating a market in which capacity is no longer moving uniformly.
AIG has not announced any change to underwriting appetite, pricing or distribution alongside the appointment, but the businesses falling under Signorelli’s remit include lines where insurers are increasingly having to decide how aggressively to compete for premium and where to hold firm on terms.
