Detective Gardell, 52, is also accused of using his police contacts to provide confidential information to organized-crime members. Federal prosecutors said that he had passed along confidential information about continuing investigations, influenced a city police investigation into one of the conspirators, assisted in obtaining firearms permits for organized- crime members and provided law enforcement parking permits to organized-crime members. In return, they said, Detective Gardell received cash and property including money for a new pool at his house, rooms and meals at casinos in Las Vegas and Atlantic City, and a fur coat.

Prosecutors said the scheme to use the detectives union money was never carried out and the union never lost any money. Yesterday afternoon, Detective Thomas J. Scotto, the union president, said that Detective Gardell never approached the union's officers about investing union money in any companies named in the charges. He said the union, which only invests in large, established companies, would have rejected the suggestion if it had been made. Detective Gardell's lawyer, Joseph Tacopina, said yesterday that his client maintained his innocence.

According to the indictment, the defendants conspired to divert money from the detectives' retirement fund and from another union pension fund to Husic Capital Management, a San Francisco investment firm that manages $4.5 billion for big companies and pension funds.

The indictment charged that the chief investment officer of Husic, William Stephens, then planned to use some of the money to buy stock from a company that would kick back 20 percent of the money to the defendants. By skimming from the members' retirement savings, the defendants could reap millions of dollars in illegal profits, the indictment said.

By using Husic as an intermediary, the defendants hoped to conceal the skimming, said Richard Walker, enforcement director for the Securities and Exchange Commission. ''This is a very important case from our point of view,'' he added.

A Husic spokeswoman, Abigail Baker, said the company would cooperate with law enforcement officials and had suspended Mr. Stephens when it learned of his indictment. ''The firm as a whole is completely shocked,'' Ms. Baker said.

At 6 a.m. yesterday, more than 600 F.B.I. agents began rounding up nearly 100 defendants throughout the city and as far away as Texas, Utah and California. Investigators coordinating their efforts through New York charged 120 people in 16 indictments and 7 criminal complaints. Prosecutors said that 10 of the people charged yesterday were reputed members or associates of organized crime. They said it was the largest number of people ever arrested at one time on stock fraud charges and one of the largest groups ever arrested by the federal government.