The secret behind the success of CFDs here 10 years ago was that they generated obscene profits for Irish brokers — eclipsing the margins they earned at the time from their traditional private client business and their dealings in Irish shares.

Seven years after the market instruments known as Contracts for difference — or CFDs — helped destablise Anglo Irish Bank and added to the country’s huge losses from the fallout of the banking collapse, they are again causing the regulators here some concern.