Shares in CPP Group, which helps victims of identity theft, yesterday crashed 23 per cent after it warned annual profit would be "significantly" lower thanks to an investigation by the City watchdog.
The credit-card insurer has seen its revenues hampered by a Financial Services Authority probe into its sales techniques.
The investigation, which began in March, led Barclaycard, one of CPP's major partners, to suspend sales of some of its products.
Yesterday CPP admitted the length and outcome of the FSA's investigation were still uncertain.
Shares in the company dropped by 22p to 117p.