London-based Antares Managing Agency Limited reported that Martin Sullivan has been appointed as non-executive chairman.

Sullivan began his insurance career in 1971 with American International Group (AIG), where he served for 37 years ultimately becoming president and CEO in 2005. At that time, he replaced Maurice Greenberg who was facing scrutiny by then-New York state Attorney General Eliot Spitzer and federal regulators.

In June, 2008, as AIG continued to suffer record losses from risky mortgage products, Sullivan was himself replaced by former Citigroup banker Robert Willumstad, who was already AIG chairman.

In 2010 Sullivan joined Willis Willis Group Holdings as deputy chairman and CEO of the Willis Global Solutions unit. However, he left Willis in May of 2013 to “pursue other interests,” according to the firm.

Antares offers property, casualty, marine and aviation underwriting and claims services on a worldwide basis.