Federal Court proceedings have been issued in a shareholder class action against Commonwealth Bank, being heralded as the largest in Australian legal history.

Law firm Maurice Blackburn on Monday said a statement of claim filed in the Federal Court in Victoria names outgoing chief executive Ian Narev and current chair Catherine Livingstone as being among those who knew CBA had been accused of breaching anti-money laundering and counter-terrorism funding laws.

Litigation funder IMF Bentham said its funding of the class action – which centres on the lender’s failure to promptly disclose the 2015 allegations to the market – is now unconditional.

Maurice Blackburn national head of class actions Andrew Watson said that when CBA did reveal the issues to the market this year, the result was a significant drop for an otherwise stable stock.

“Our investigations and analysis show that this drop was in the top one per cent of price movements that CBA experienced in the past five years, so clearly the news was of material significance to shareholders,” Mr Watson said in a statement.

The ABC reported Mr Watson as saying the case would be one of the largest shareholder cases in Australian legal history.

He said there had already been an “overwhelming” interest in the class action from thousands of retail and institutional shareholders.

“This will be a very large case, I think running into the hundreds of millions of dollars,” Mr Watson told the ABC.

“It’s a very large number of shares that would have been acquired during that period.”

IMF said the start of the class action claim period has been extended back by more than six weeks and is now open to those who purchased CBA shares between July 1, 2015 and August 3, 2017.

Registrations for the class action, which has the potential to be the largest ever in Australia, opened last month.

Maurice Blackburn alleges CBA breached its continuous disclosure obligations, and made misleading and deceptive public statements claiming performance of its obligations under the Anti-Money Laundering and Counter-Terrorism Financing Act.

Maurice Blackburn has said CBA knew about its potential breaches of anti-money laundering and counter-terrorism financing laws in 2015 but only told the stock exchange in August this year after the financial intelligence and regulatory agency took civil action.

AUSTRAC is accusing CBA of more than 53,500 contraventions, most of them related to the bank’s use of intelligent deposit machines (IDMs) – ATMs that accept cash and cheque deposits which are immediately credited to the nominated recipient.

AUSTRAC claims the bank failed to assess the money laundering and terror financing risk of the machines before they were rolled out, and to provide on time 53,506 reports of IDM transactions of $10,000 or more.

CBA shares were 50 cents, or 0.66 per cent, higher at $76.80 at 1127 AEDT.

Commonwealth Bank has not commented on the action.