The handful of publicly traded asset managers implicated in the mutual funds trading scandal have had more than $6 billion (€5.04 billion) wiped from their market value since the probe began, as investors sold on concerns about the effect the probe would have on the fund profits.

A dozen companies managing a total of $1,500 billion, about 20 per cent of the US industry's assets, have been implicated in the scandal, with their involvement ranging from minor wrong-doing to criminal charges. Brokers from another two firms, Merrill Lynch and Citigroup, have also been implicated.

More than 40 people have lost their jobs and some 30 lawsuits have been filed over the scandal, which centres on the improper trading of mutual fund shares.

As a result of the probe, fund companies are facing a double whammy likely to sharply cut profits just as they emerged from the three-year bear market. All the groups named have suffered from big outflows of money, which will reduce their revenue.

At the same time, there is rising pressure for funds to cut fees, which will further shrink revenue.

Morningstar, an influential fund tracker, has, in an unprecedented step, recommended investors either sell or steer clear of Janus Capital, Fred Alger Management, Strong Capital Management, Federated Investors, Alliance Capital, Bank of America's Nations Funds, Bank One and Putnam Investment.

Amvescap, Marsh & McLennan (which owns Putnam), Janus, Federated and Alliance Capital have lost more than $6 billion in share value since news of their involvement emerged. UK-based Amvescap, which generates 80 per cent of its revenues in the US, has been especially hard hit, losing $1.5 billion.