Guinness Mahon was an Irish merchant bank originally based in Dublin but more recently with operations in London.
The firm was founded as a land agency in Dublin in 1836 by barrister Robert Rundell Guinness, a great-nephew of the brewer Arthur Guinness,[2] and John Ross Mahon, an estate agent.
[3] A London office opened in 1873, closed in 1916 during World War I and then re-opened again in 1923.
[3] The firm decided to enter the securities market buying White & Cheeseman, a stock jobber, in April 1984.
The offshore investment activities in Australia and New Zealand (then known as Guinness Peat Group) were bought by Brierley Investments Limited (a business controlled by Sir Ron Brierley) in 1990[7] and the Guinness Mahon investment banking business was acquired by Bank of Yokohama in 1991[6] and then sold on to Investec in 1998.