CNA Re, which was acquired last week by Tawa UK, has changed its name to CX Reinsurance Company.
Chief executive Philip Singer said: "It was a term of the sale that we should change the name, and in choosing CX Re we have chosen a name that reflects the company's close associations with the City, where for many years it has been one of the leading reinsurance companies."
By forming CNA Re the company is hoping to build a "significant presence" in the non-life run off market.
Tawa UK was formed in 2001 to acquire and manage property and casualty insurance and reinsurance companies in run-off.