Shares in U. K.-based inter-dealer broker ICAP PLC reported a massive fall on Friday after the company cautioned that full-year pretax profit would be lower than in the previous year, reducing its guidance as some of its latest businesses struggle to break even.

Michael Spencer, ICAP founder and chief executive, hammered home on repeated earnings conference calls how ICAP was well-positioned with its initial post-trade processing businesses to profit from a shift of business to the less flamboyant back-office pointing that US lawmakers are busy writing into law.

On Thursday, committee chairman Chris Dodd revealed that it would be difficult to write legislation on the prop ban "as specific maybe as Paul Volcker recommended". That clearly signifies just how lawmakers are now fiddling with themselves.

At 0851 GMT, ICAP shares reported a 16% down at 306 pence while the FTSE100 index was down 1.3%.

It's been disturbing for shareholders on Friday morning - with ICAP off 18 per cent at one point - but no wonder Mr. Spencer has changed his tune.

The company claimed that revenue for the fiscal third quarter ended December was marginally exceeded that of the same period last year as new business segments offset a decline in its core voice revenue.