Jay Fishman, one of two co-chief operating officers at Citigroup, has been appointed chairman and chief executive of insurer St Paul Companies, succeeding Douglas Leatherdale.
Leatherdale said: "Jay is uniquely qualified to build upon St Paul's global specialty insurance focus, superior positioning with independent agents and brokers and bedrock financial strength."
St Paul, which provides commercial property liability insurance and non-life reinsurance worldwide, reported $8bn (£5,54bn) revenues for 2000 from continuing operations. Total assets for 2000 were $35.5bn (£24.6bn).
The company's headquarters are based at St Paul, Minnesota, in the US. It is ranked at 222 on the Fortune 500 list of largest US companies.
Fishman had wide-ranging responsibilities at Citigroup, serving as chairman and chief executive officer of its Travelers insurance unit, as well as overseeing financial and risk management functions globally.
He had been regarded as a potential successor to Sandy Weill as head of Citigroup.
Fishman's responsibilities at Citigroup are to be divided. Chuck Clarke will become head of Travelers Property Casualty and George Kokulis will take over Travelers Life and Annuity.