The corporate regulator framed a number of allegations against ANZ on Friday including that ANZ manipulated the bank bill swap rate (BBSW).
ASIC alleged that ANZ was "seeking to maximise its profit or minimise its loss to the detriment of those holding opposite positions to ANZ's".
As recently as 12 February 2016, ASIC chairman Greg Medcraft warned banks to "plead guilty" when it comes to BBSW manipulation.
"We can either have a contested outcome in the court or we can have an agreed outcome in the court," Mr Medcraft said at the time.
He also drew attention to ASIC's $80 million 'war chest', which will help fund the regulator's legal battle against ANZ.
ANZ said in a statement on Friday that it rejects the allegations and will "vigorously defend" itself in the case.
The bank's chief risk officer Nigel Williams said ANZ has "cooperated fully with ASIC's investigation over many months, at a cost of many millions of dollars".
"This includes actively seeking to resolve the Commission’s concerns since January 2015,” Mr Williams said.
"We believe the Commission’s statement of claim is based on a misunderstanding of how bank bill issuance and interest rate risk management operates and the limited case law which applies to this area," he said.
"Our practices in the BBSW market were consistent with Australian market practices in wholesale financial markets and we reject ASIC’s characterisation of the transactions in question."
Mr Williams said ANZ will continue to review the question of chat messages between traders, adding that the bank has already dealt with chats and behaviours that breach its code of conduct through internal disciplinary action taken against the individuals involved.
"Since June 2014 we have also engaged ASIC about chat messages between ANZ traders," he said.
"We do not agree, however, with ASIC’s characterisation of the issues related to the chat messages. It is now for the courts to provide clarity on trading practices."
ANZ noted that ASIC’s legal action will likely take considerable time to resolve through the courts and the matter of penalties is also uncertain.
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