For the biggest of the big four Australian banks there's been a huge, rare blow to the bottom line.

After posting eight years of record profits Commonwealth Bank has a record fine - the largest in Australian corporate history at NZ$760 million.

Australia's financial intelligence unit AUSTRAC found the bank failed to flag suspicious transactions, breaching money laundering and anti-terror laws more than 53,000 times.

Every transaction over AU$10,000 must be reported to Australian authorities, but the bank's Intelligent Deposit Machines reported nothing for three straight years.

In that period, the bank admits, millions of dollars were laundered to drug syndicates offshore. The penalty could've been larger, a maximum of more than AU$1 trillion.

A clear sign that the market knew the bill could've been much bigger came after the fine was announced, which saw a rise in share price.

But $760 million is still 15 times larger than the previous record. Australia's treasurer says customers should not foot the bill.

"I warned the banks not to do that, because people would form a very unfavourable view," said Scott Morrison.

That includes New Zealand consumers, as Commonwealth Bank is the owner of ASB Bank.

But ASB doesn't use the same failed systems, and said in a statement that "the fine does not, and will not, directly impact ASB customers."

For Commonwealth Bank however, the message is clear.

"That should send shockwaves right across the financial services firms - and right across the country," Home Affairs Minister Peter Dutton said.

Australia's big four banks may post huge profits, but breaches draw the fines to match.

Newshub.