In a scandal that rocked the world's two biggest auction houses, the former chairman of Sotheby's was convicted Wednesday of plotting with his counterpart at Christie's in a price-fixing scheme.

A Manhattan jury deliberated two days before rejecting defense portrayals of millionaire A. Alfred Taubman as someone who dozed off in important meetings and lacked a grasp of finance needed to pull off a complex conspiracy.

"I don't care if you fall asleep or not," mail carrier Mike D'Angelo, the jury foreman, told reporters outside U.S. District Court. "You're there, and you know what's going on."

Taubman, 76, of Bloomfield Hills, Mich., had denied charges he and former Christie's Chairman Anthony Tennant stole as much as $400 million in commissions from sellers of fine art from 1993 to 1999 through the scam. Between them, the businesses control more than 90 percent of the world's art auctions.

Taubman faces up to three years in prison at his April 2 sentencing on conspiracy to violate antitrust laws.

"We were, of course, disappointed in the verdict," said defense attorney Robert Fiske. "We'll review our options and decide what to do next."

Taubman, wearing amplifying earphones, sat stiffly at the defense table for several minutes after the verdict was read. He declined to speak with reporters.

The prosecution's case hinged on the credibility of Diana "DeDe" Brooks, the former chief executive of Sotheby's, who pleaded guilty in October 2000 to price-rigging charges, and on that of her counterpart at Christie's, Christopher Davidge.

Brooks agreed to testify against Taubman in hopes of avoiding a three-year prison sentence; Davidge had been granted immunity.

Brooks, 51, claimed the plot was conceived during a secret 1993 meeting in London at which Taubman and Tennant agreed they "were killing each other on the bottom line, and that it was time to do something about it."

During their testimony, Brooks and Davidge said their bosses ordered them to end a costly rivalry by eliminating discounts and charging identical, non-negotiable commissions. Brooks said Taubman also warned her to keep quiet about it.

Brooks "was a convincing witness," said juror Dorothy Fronk, a school administrator. "Davidge was also."

In his closing arguments, defense attorney Fiske had called Brooks "a walking reasonable doubt." The defense accused her of single-handedly hatching the plot to fix prices on sellers' commissions during a February 1995 meeting in the back seat of her Lexus with Davidge.

"We agree with the prosecution that a crime was committed," Fiske told the jury. "The question for you is whether Mr. Taubman had anything to do with that agreement."

Prosecutor John Greene, of the Justice Department's antitrust division, countered that Taubman had the means to carry out the scheme — and the motive: Sotheby's profits plummeted in the late 1980s, from $410 million in 1989 to $202 million in 1992.

As chairman of the company and a real estate mogul, Taubman "thought he was above the law," Greene said. "You don't become a millionaire without knowing how to read the bottom line."

Tennant, 71, of Andover, England, has said he will not come to the United States to face charges, and the antitrust case is not covered by extradition treaties.

Sotheby's pleaded guilty to conspiracy and was sentenced to pay $45 million. Christie's was granted amnesty by the government for its cooperation.

Earlier this year, a federal judge approved a $537 million settlement of price-fixing lawsuits brought by customers of Sotheby's and Christie's. The auction houses are sharing the cost of the settlement.