In the four days since New York Attorney General Eliot L. Spitzer alleged that brokers and corporate insurance carriers were engaged in bid-rigging and secret payoffs, three big industry players have dropped the commissions that Spitzer blamed for the problems.

Insurers American International Group Inc. and Ace Ltd. confirmed Monday that they would no longer pay "contingent commissions" to brokers for sending them insurance business. The world's largest insurance broker, Marsh & McLennan Cos., announced Friday that it would no longer accept such commissions despite having brought in $845 million from them last year. Spitzer charged the company and its Marsh Inc. subsidiary with civil fraud on Thursday in a complaint that named -- but did not charge -- AIG, Ace and several other insurance companies.

The three companies' decisions to abandon a widely accepted insurance industry practice are testimony to Spitzer's growing national influence and his ability to use individual cases to force structural change, legal and industry analysts said.

Though Wall Street insiders belittled his first allegations of biased investment banking research, he ultimately forced a $1.4 billion settlement and a restructuring of banking research. Similarly, his probe of improper mutual fund trading has netted more than $2 billion in fines, restitution and fee reductions.

"Success breeds success," said former prosecutor David Gourevitch. "Firms understand that they ignore his issues at their peril . . . [and] the sooner you get with the program, the better your deal is."

The insurance companies may also be bowing to market reality, because the schemes' alleged victims -- large companies that needed liability insurance -- already are lining up lawyers to help renegotiate their insurance contracts and recover their alleged losses.

"I've been getting one call after another from general counsels of big companies, saying, 'We are Marsh [or other big brokerage firm] clients. . . . What should we do to find out if we've been ripped off?' " said Los Angeles attorney David E. Wood, who specializes in suing insurance companies for corporate clients. "There's no way a corporation is going to pay these commissions" in the future.

More than a dozen other large insurance brokers and carriers also are under investigation, and Spitzer said his office has evidence that the commission arrangements have led to higher premiums not only for corporate insurance but also for individuals seeking life and health insurance coverage.

Two AIG executives and one Ace official pleaded guilty last week to submitting phony or inflated bids to help Marsh brokers steer particular contracts to other carriers. Sources familiar with Spitzer's investigation said more criminal and civil charges are coming, as industry participants fall all over themselves to share information and cooperate with the New York regulators.

Brokers Aon Corp. and Willis Group Holdings Ltd. have said they are cooperating with Spitzer's office, as have two other carriers mentioned in Spitzer's complaint against Marsh, Hartford Financial Services Group Inc. and Chubb Corp.

Leaders of the $200 billion corporate property, casualty and liability insurance market say they expect the scandal to spark broader changes in the use of contingent commissions. At minimum, they said, brokers will have to be more forthcoming with their customers about commissions they receive from insurance companies.

"What the industry wants to do above all is maintain the confidence of its customers," said Robert P. Hartwig, chief economist for the Insurance Information Institute, an industry trade group. "There's almost general consensus that there will be changes in the degree, extent and nature of the disclosure of fee payments."

Spitzer's probe also appears to be sparking concern in another segment of the insurance industry, in which carriers reward brokers for the volume and quality of business that they receive.

Spokesmen for three large carriers that offer group life insurance -- MetLife Inc., Cigna Corp. and UnumProvident Corp. -- said yesterday that they are reviewing their use of the commissions in light of Spitzer's allegations against Marsh. All three companies had previously confirmed that they had received subpoenas from Spitzer's office in connection with the probe. Prudential Financial Inc., a fourth carrier that offers group benefits, has acknowledged receiving a subpoena from Spitzer, but a spokesman declined to comment further.

A civil suit filed last week in San Diego by the class-action firm Lerach Coughlin Stoia Geller Rudman & Robbins LLP suggests how that portion of the probe might eventually help individual consumers. The lawsuit alleges that Universal Life Resources, a broker that helps companies select group insurance, took kickbacks from carriers that then charged higher prices for individual coverage to cover the costs of the kickbacks.

Lead plaintiffs' attorney John J. Stoia Jr. said the firm's research suggested that employees are paying from $5 to $12 apiece to fund the broker payments.

A Universal Life spokesman denied that any improper relationship existed between the broker and the carriers but declined to comment further.

Eliot L. Spitzer announced the insurance probe on Thursday.Jean-Baptist Tateossian, foreground, manager of national accounts for AIG, pleaded guilty to felony fraud in the insurance probe.