The top four Australian-owned trading banks have collectively made more money in the four years since the global financial crisis than the four before it.
The ANZ National, BNZ, Westpac and ASB made $14.42 billion between 2008-2011, a $340 million increase from $14.08b between 2004-2008.
The Green Party today released the research prepared by the Parliamentary Library.
A similar analysis of all New Zealand industries in the four years following the crisis revealed a 15 per cent drop in profits.
Green co-leader Russel Norman said excess profits in the banking industry and the high level of foreign ownership in the sector was causing long-term damage to New Zealand's economy.
"Outgoing Reserve Bank governor Alan Bollard last week admitted that New Zealand's big four Australian-owned banks earn more out of New Zealand than banks in most other countries."
Dr Norman said Mr Bollard's complacency over the issues was "astounding".
He said the challenge for Mr Bollard's successor, Graeme Wheeler, was to promote competitive behaviour in the sector so the rest of the economy didn't suffer due to excess profit-taking.
Dr Norman said New Zealand banks make up only six per cent of the sector and called for Kiwibank and other New Zealand-owned banks to be strengthened.
"By injecting capital into Kiwibank and allowing it, in time, to become the Government's banker, we can increase its capacity to compete fairly with much bigger Australian banks.
"Kiwibank can also be the retail arm of our proposed default KiwiSaver provider," said Dr Norman.