Even those companies currently not in Mr. Spitzer's investigative crosshairs are not safe from such lawsuits, if it can be determined that they have paid contingent commissions and participated in the so-called Placement Service Agreements, according to one insurance-law expert.

According to Fred Isquith, attorney at the New York-based Wolf Haldenstein Adler Freeman & Herz LLP, all these cases have strong merit, assuming the facts bear them out. "These cases have merit, absolutely. They're good cases," Mr. Isquith argued.

These lawsuits, representing shareholders of companies that had participated in insurer-broker contingency fee arrangements, raise a number of similar issues: They allege that the company in question was paying "illegal and concealed contingent commissions."

The actions claim that the hidden payments resulted in "grossly overstated" reported revenue and income, and that the company is subject to enormous fines and penalties totaling potentially hundreds of millions of dollars. The lawsuits also charge that these companies "violated federal securities laws" by making materially false or misleading public statements.

One of the latest companies that has been targeted in such complaints is Axis Capital Holdings, which was named in two lawsuits seeking class-action status filed late last month.

Axis representatives declined to comment, and the two law firms that have filed the lawsuits, Lerach Coughlin Stoia Geller Rudman & Robbins LLP and Schatz & Nobel P.C., did not return calls seeking comment.

But in Axis' case, there is one additional factor that may complicate the allegation of illegal business activities: The company is 9.7-percent owned by Marsh & McLennan, through direct stock ownership and a private-equity partnership called Trident II that is managed by Marsh's MMC Capital unit.

Axis also receives a significant amount of business from Marsh?in its registration statement July 2003, Axis had disclosed that about 40 percent of its business comes from Marsh.

"I think all these cases involve a major, industrywide problem. It wouldn't surprise me at all if this was beginning of a demonstration of major corruption within much of the insurance industry," Mr. Isquith said.

He also speculated that companies such as Axis that had particularly close financial ties to Marsh & McLennan could be especially vulnerable to litigation, even if they have not been cited in New York attorney general's civil suit.

"Let's assume that Marsh owns a piece of Axis, and then Marsh directs business to Axis because, after all, Marsh is going to get a piece of the profitability back from its ownership and in addition, also get to have Axis pay extra commissions into Marsh. So you tell me whether [Marsh's ownership] is a relevant factor," said Mr. Isquith.

"Paying contingency fees involves a business model that is not only ethically questionable and possible illegal, but also unsustainable," Mr. Isquith said, "because as we can see, once this came out in the light of day and people began to focus on it, they realized the kinds of conflicts of interest these companies were engaged in."