The ANZ's head of international and institutional banking, Alex Thursby, is taking another post. Mr Thursby joined ANZ - Australia's third largest bank by market capitalisation - six years ago from Standard Chartered, the Asia-focused British bank. He has been a key player in ANZ's ambitious expansion in Asia. The 53-year-old has also been named as a candidate to eventually replace ANZ chief Mike Smith. Mr Smith said he expected to serve in the role for another two to three years. Mr Smith said Mr Thursby's new role "represents a natural next step in his international banking career and more recently he has had a personal desire to be closer to his family's base in the United Kingdom." Both ANZ and market analysts said Mr Thursby's resignation had come out of the blue. "It comes as a surprise but ANZ has a depth of talent on Asia," Bell Potter Securities analyst TS Lim said. The guys who are looking after their Asia push all have very relevant experience and very strong business relationships in that region. While Alex was a leader, they have people who can step up to the plate. The bank's Asia business contributes about 15 per cent of earnings - a figure it expects to rise to between 25 to 30 per cent by 2017. "The business is performing very well," Mr Lim said. The momentum has been built up with Alex and ANZ has the people who can step up to continue that. ANZ chief executive of Asia Pacific Gilles Plante and managing director of global markets Steve Bellotti will manage Mr Thursby's responsibilities from May 1 while the bank looks for a replacement. Mr Thursby will take over from Michael Tomalin at the National Bank of Abu Dhabi on July 1. ANZ shares fell 1.9 per cent to close at $28.27. The Commonwealth Bank also lost ground, with its shares closing 0.7 per cent lower at $68.45.