Commonwealth Bank of Australia matched expectations for flat second-half earnings, and warned of a challenging year ahead due to volatile global markets and upward pressure on funding costs, sending its shares down over 2%.

Australia and New Zealand Banking Group, Australia's third-biggest lender, said on Monday it was likely to book provisions of around $1.1 billion in its second half due to the ongoing deterioration in global credit markets.

National Australia Bank, the nation's top lender, booked another A$830 million ($798 million) in losses from its exposure to U.S. mortgages, sending its shares down as much as 13 percent.