Police made eight arrests today in connection with a major probe by the City's financial watchdog into insider dealing.
The operation, which involved 40 Financial Services Authority (FSA) staff and City of London Police, saw a number of properties searched across London and the South East.
The FSA, which refused to give any further details of the case, said the move was part of its "ongoing work to combat market abuse".
The authority is looking to step up its enforcement activity over insider dealing with three cases currently before the courts.
The eight people arrested were all men aged between 27 and 48, the FSA added.
The watchdog is currently looking for greater powers to combat market abuse and is determined to shrug off a "light touch" reputation.
FSA chiefs told MPs in May that powers to strike plea bargains with offenders - similar to those used by US regulators - would form part of a "bold and more resolute" approach to enforcement.
Then-chairman Sir Callum McCarthy said the problem of market abuse was not taken seriously enough in the City.
The FSA is beefing up its enforcement as well as improving its monitoring of financial markets through the upgrade of its transaction monitoring system, known as Sabre.
The regulator is also putting a greater emphasis on criminal prosecutions to present a greater deterrent to potential wrongdoers threatened with the prospect of jail if caught.
The FSA has investigated several cases of market abuse including the spread of false rumours surrounding the funding position of Halifax Bank of Scotland, which hit the mortgage lender's share price in March.Reuse content