The credit crunch sparked a 58 per cent rise this year in class-action lawsuits filed by American shareholders against companies and their directors, research shows.

Lawyers filed 207 class-action cases this year, up from 131 in 2006. The average settlement also soared to $32.2 million (£16.2 million), up nearly 50 per cent on 2006. The median pay-out hit a high of $10 million, according to NERA Economic Consulting, an international firm of economists.

So-called mega-settlements, worth $100 million or more, accounted for nearly one in twelve of all settlements. Before 2000 they accounted for, at most, 2 per cent of payouts.

Until September, NERA forecast the volume of class actions to rise only 12 per cent this year. The onset of the credit crunch and multibillion-dollar writedowns by investment banks triggered a wave of lawsuits, however.

Just before Christmas, Morgan Stanley and its global director of human resources received a class-action suit filed on behalf of members of the bank’s pension plan, The Times has learnt.

The suit is likely to result in a claim for hundreds of millions of dollars. Morgan Stanley is accused of allowing its pension plan to invest in the investment bank’s shares for the past two years “while such stock traded at artificially high prices”. This happened, the claim alleges, because of “misinformation” over the bank’s operations “while Morgan Stanley exposed itself to the highly risky and tenous subprime mortgage market”.

The NERA report gives warning of further increases in the volume of class-action lawsuits next year as more problems emerge in the wake of the credit crunch. The report states: “Subprime lending cases are springing up across several federal circuits. As the crisis in the credit markets continues to deepen and the market for subprime mortgages suffers accordingly, more litigation is likely to follow.”

One of America’s most prolific class-action law firms asked the courts to sanction nearly $700 million in legal fees last month for helping investors to recoup losses from the collapse of Enron, the failed energy trader. If approved, Coughin Stoia Geller Rudman & Robbins will enjoy the largest legal payday in history.

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