Fifteen specialists who managed trades on the floor of the New York Stock Exchange used their positions to earn an estimated $20 million in illicit gains for themselves and their firms, federal authorities charged yesterday.

The Securities and Exchange Commission also filed civil charges against 20 specialists, including the 15 charged in the criminal indictment, and the NYSE as well. An SEC official decried the violations as “profound and, at times, profane.”

Federal authorities said that between 1999 and mid-2003, specialists at five firms put their companies’ orders ahead of customers’ orders, causing those customers to get inferior prices.

“Over time, these small thefts accumulate into large profits that translate into higher compensation and bonuses for specialists who execute the trades,” U.S. Attorney David Kelley said at a Manhattan news conference.

Specialists run the open-outcry auctions on the floor of the NYSE, matching buy and sell orders for customers of the stocks they oversee. They also use their firms’ money to buy shares when nobody else wants to buy and to sell shares from their own inventory when nobody else wants to sell.

The defendants were expected to “refrain from trading for their firm’s proprietary account except when necessary to maintain a fair and orderly market,” said Mark Schonfeld, director of the SEC’s New York office. “The specialists named in today’s action showed a disregard for their legal duty that was both profound and, at times, profane.”

Fourteen were awaiting arraignment in federal court in Manhattan on multiple securities fraud charges; the 15th was believed to be in Europe. If convicted, they face up to 20 years in prison and fines of up to $5 million.

A settlement with the SEC requires the NYSE to spend $20 million on regulatory audits through 2011, Mr. Schonfeld said. The exchange also agreed to implement a pilot program of electronic surveillance of its trading floor for 18 months.

The NYSE’s regulatory enforcement arm also announced charges against 17 former specialists, including those indicted, in connection with the case.

Responding to the SEC charges and settlement, the NYSE’s chief regulatory officer, Richard Ketchum, noted that the exchange revamped its enforcement arm starting in late 2003.

“Our board and entire organization are committed to take whatever additional steps are necessary … to meet our surveillance and enforcement obligations,” Mr. Ketchum said

Last year, NYSE specialist firms paid a total of $247 million to settle the same allegations brought by the SEC.

The firms’ profits come from fees on each transaction as well as their own stock trading. Critics of the specialist system claim this is an inherent conflict of interest, while the NYSE has noted that the specialist firms gained $155 million in illegal profits over five years, a time when the exchange handled $50 trillion in trades.