In what could be Australia’s biggest class action ever, some 40,000 people have signed on to litigation that challenges overdraft and late fees charged by a dozen of the country’s largest banks, the Sydney Morning Herald reports.

The Morning Herald reports that the litigation — actually a series of claims brought by Australian plaintiffs firm Maurice Blackburn — could eventually attract up to 100,000 people and businesses on the plaintiffs’ side. That would make it the largest class action in Australia’s history. Among the defendants: Australia and New Zealand Banking Group, Commonwealth Bank Group, National Australia Bank and Westpac Bank, as well as international banks like HSBC and Citibank.