"The consequences of the potential proceedings could be significant and would be credit negative for ANZ," Frank Mirenzi, vice president of Moody's Investors Service, said in emailed remarks on Friday.

"Whilst, at this stage, there is material uncertainty with respect to any potential outcomes from these proceedings, in the short-term they are likely to create further challenges for the bank's brand and reputation."

ANZ faces the charges over a $2.3 billion share issue in 2015, along with underwriters Deutsche Bank and Citigroup.

(Reporting by Tom Westbrook; Editing by Stephen Coates)