In 1922, W. Clement Stone, with a borrowed $100, started Combined Registry Company[1] in Chicago.

[2] Between 1959 and 1963 the company expanded into Australia, then Puerto Rico and the Bahamas, then into Europe with the addition of England[3] and Northern Ireland.

(ISBN 978-0-671-52462-3) In 1980, shareholders of Combined Insurance Company of America approved the formation of a holding company, Combined International Corporation, which traded publicly on the New York Stock Exchange under the call letters PMA (standing for "Positive Mental Attitude", a Stone catchphrase).

The new company was renamed Aon – a Gaelic word signifying oneness and unity – in 1987.

[4] In 2008, Aon sold Combined Insurance to ACE Limited for $2.56 billion[5] which resulted in the closure of the UK employee benefits arm.