Chief executive Mike Smith continued to stand by the bank's board yesterday, saying it shouldn't be held accountable for problems at its securities lending business.

The head of Australia's fourth-biggest bank declined to detail its level of exposure to B&B, whose market value has declined by more than 90 per cent since November as investors lost confidence its debt-laden business model.

''We don't give away our customers' exposure,'' Mr Smith told ABC TV, adding that the bank had not yet struck a specific provision against its exposure to B&B.

''It's hard to see how that one will unfold but at present I think the situation with the company is still unravelling,'' he said.

''We'll have to wait and see.''

In what is already shaping up to be a horror year for the bank, ANZ announced last month that its annual cash profit would dip by up to a quarter after it set aside $1.2 billion in provisions on bad loan exposures, including loans to failed broker Opes Prime.

On Friday, ANZ sacked eight staff, including the head of its institutional bank and its chief risk officer, after finishing a review of its securities-lending business, which included its relationship with Opes.

Mr Smith said yesterday that the Opes debacle did not indicate systemic problems at the bank.

''However, I don't believe that there is a culture which is sufficiently robust to prevent it rehappening, so therefore there has got to be some remedial action,'' he said.

Levels of accountability should be realistic and suit the situation, Mr Smith said, adding that, although the bank had suffered ''very significant'' reputational damage, the securities lending business was a very small part of the bank's business.

''I think it's management.

''The management and the CEO run the business: we're the ones who are accountable for the bank.'' He would not say whether entering into mediation with Opes Prime's administrator, John Lindholm, indicated that the bank wanted to settle with Opes clients.

Opes clients have launched a class action against ANZ, which took ownership of shares lent by the broker that the clients believe were their property. ''It's a question of do you want 20 years of protracted litigation and reputational issues or do you want to come to something which is a bit more convenient? ... it's a balance.''

On the global economic environment, Mr Smith tipped further consolidation of smaller banks but said large banks were probably too big to fail. AAP