Rob Thomas is to retire from his post as chairman of Citigroup's corporate and investment bank in Australia and New Zealand after 18 years with the bank and its predecessor businesses. His last day in the office will be 30 September.

In retirement, Thomas will maintain his interests in a number of projects, including a new role as vice chairman of Benitec, a world-renowned gene silencing group. He will also act as a consultant to Citigroup and represent the organization in a number of its community initiatives including VisAsia and the Australian Indigenous Leadership Program.

Thomas' long banking career included many years with Potter Partners and County NatWest Securities - a group that in the late 1980s grew to become one of Australia's dominant stockbrokers.

Following Salomon Smith Barney's acquisition of the local County Natwest franchise in 1999, Thomas was appointed managing director of equities, and later, chief executive Salomon Smith Barney Australia/NZ.

At the time of the re-branding to Citigroup and the formation of the corporate and investment banking group in 2003, Thomas was appointed chairman of the group for Australia and New Zealand.

Chief executive officer of the group, Stephen Roberts, says: "Rob's distinguished career in capital markets and investment banking spans many decades and includes a pivotal role in the development of Citigroup in this part of the world. He now believes it is time for a change of focus and greater work flexibility."

"Rob has seen great change in this company and the industry over his distinguished career. On behalf of his many friends and colleagues within the firm, I wish to sincerely thank him for his outstanding contribution and commitment," says Roberts.