NEW YORK—A New York state judge has thrown out the convictions of two former Marsh Inc. executives previously found guilty of bid-rigging charges.

In a ruling Friday, New York County Supreme Court Judge James A. Yates overturned the convictions of former Marsh Managing Directors William Gilman and Edward J. McNenney, saying contradictory evidence disclosed in a later trial “undermines the court’s confidence in the verdict,” according to court documents.

The men, the first former Marsh executives to face trial in the case, were convicted in February 2008 of violating New York antitrust law but acquitted of 20 other counts of fraud and larceny. They had been sentenced to 16 weekends in jail but appealed their convictions.

The ruling followed Judge Yates’ decision earlier this year to reduce or dismiss criminal charges against more than a dozen former executives who had pleaded guilty in the case. Vacating the convictions of Messrs. Gilman and McNenney means that none of the convictions or guilty pleas resulting from proceedings initially brought by former New York Attorney General Eliot Spitzer have been upheld.

“We are very pleased with the Judge’s decision,” Scott D. Devereaux, a partner with Cooley Godward Kronish L.L.P. in Palo Alto, Calif., who represents Mr. McNenney, said Tuesday.

A spokesman for New York Attorney General Andrew Cuomo’s office, which inherited the case from Mr. Spitzer, did not immediately respond to a request for comment.

In January, attorneys for Messrs. Gilman and McNenney filed what is called a 440 motion that asked Judge Yates to vacate the convictions due to prosecutorial misconduct.

The motion was based on “multiple forms of exculpatory evidence” that prosecutors failed to produce during the trial of Messrs. Gilman and McNenney, but did disclose it in a later trial against three other Marsh executives, all of whom were acquitted, according to documents.

In his ruling, Judge Yates said some of the nondisclosed material “would have been invaluable to the defense effort” to challenge what prosecutors described as a horizontal conspiracy between individuals to rig bids for excess casualty insurance coverage.

In addition, the verdict rested firmly upon the testimony of several key cooperators “and yet each one of them, after testifying with very favorable cooperation agreements, has, at times before, during or shortly after the trial, given sworn testimony discrediting, even contradicting their trial testimony,” according to documents, the judge ruled.

Judge Yates acquitted three former Marsh executives of all charges in the case last October after a nearly 11-month trial. They are: Joseph Peiser, former managing director and head of Marsh's global broking excess casualty unit; Greg J. Doherty, former Marsh senior vp and ACE USA local broking coordinator team leader; and Kathleen M. Drake, former Marsh managing director and local broking coordinator team leader.

In November, the judge dismissed charges against three remaining defendants before their trial began. They are former Marsh Senior Vps Thomas T. Green Jr. and William L. McBurnie; and Geri Mandel, former senior vp at Zurich American Insurance Co.

Marsh itself did not face any criminal charges in the case but paid $850 million in January 2005 to end officials’ bid-rigging and fraud probes.