After fines totalling many billions of pounds from UK and US regulators, a new threat is about to hit the major banks found guilty of manipulating the foreign exchange market.
The targets include HSBC, the Royal Bank of Scotland, Barclays and US banks JP Morgan and Citigroup.
The action will be led by the US law firm Scott and Scott.
It will be of particular concern for the banks and their investors.
Why? Because many of the banks named have already paid out hundreds of millions of pounds in compensation payments following similar legal moves by Scott and Scott in the US.
Managing partner David Scott told the BBC he is confident of a similar outcome here.
He is in London before travelling to Paris and Berlin to meet complainants that are likely to include multi-national businesses, pension funds and even, he says, central banks.
"It is very safe to say that the damages suffered by the clients are in the tens of billions of dollars," he told me.
"We've been over [here] meeting with central banks, pension schemes, large multinationals who have asked us to determine if they have been harmed as a result of the conspiracy.
Banks face new legal action over forex manipulation - BBC News