While consumers might be revelling at the grilling banks are getting across the Ditch, the probe has not been good news for shareholders of Australia's major lenders.

Since the Royal Commission into Misconduct in the Banking, Superannuation and Financial Services industry was officially announced by the Aussie Government's on November 30 share prices across all the banks have slipped.

Commonwealth Bank of Australia, which owns ASB in New Zealand, has seen the biggest drop falling more than 9 per cent between November 29 and the market close on Tuesday.

Westpac is down around 7 per cent while ANZ has dropped more than 5 per cent. National Australia Bank, which owns the BNZ, has taken the smallest hit falling less than 2 per cent.

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AMP shares received a hammering last week when it admitted to the inquiry that it had charged fees for advice never given resulting in a public apology and the early exit of its chief executive Craig Meller.

AMP's share price fell 10 per cent in the week alone falling from A$4.78 to A$4.30 between its close on Friday April 13 and Friday April 20 knocking more than A$1 billion off the value of the company.

Andrew Bascand, managing director at Harbour Asset Management, says retail investors hold quite a large part of the shares in the Australian banks and have done well out of the healthy dividends paid out by the sector in the last three decades.

But since the royal commission was announced the Australian share market has risen by 7 per cent while the financial sector stocks have fallen by 0.5 per cent.

Bascand says there had been an expectation that the banks would pay out special dividends or have dividend growth this year.

"But I think that is less likely in 2018 or 2019 than it was three months ago."

Bascand points to Credit Suisse research which estimates the cost of each bank participating in the commission will be around $100 million.

ANZ has already indicated this week it will take a A$50m hit in its accounts this year.

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He expects banks will have to invest more in meeting regulatory changes, could face more fines and may have to hold additional capital as a result of the inquiry - all of which will weigh on their potential to increase dividends.

Although Bascand said there could still be the chance of one off dividends paid by ANZ or CBA if they manage to sell their wealth arms.

While the expectation of dividend growth had been taken away Bascand said he hadn't seen any sign yet of analysts making significant down-grades on the value of the banks.

A $100 million hit might seem like a big number but it is small change to the big banks.

Three of the four majors (ANZ, NAB and Westpac) are due to report half year results in the coming weeks and all eyes will be on what provisioning the banks expect to take and where they see the future going.