Thirteen people were charged in connection with insider-trading schemes involving confidential investment information passed on by employees at UBS and Morgan Stanley that resulted in $8 million in illegal profit, according to federal criminal complaints unsealed yesterday.

Separate civil charges filed by the Securities and Exchange Commission against most of the same defendants estimated that the scheme reaped even more — $15 million — in illegal profit.

Over five years, those indicted yesterday were involved in the buying and selling of hundreds of secret tips totaling millions in ill-gotten profit, prosecutors say. Two of the people indicted yesterday are charged with blackmailing others and accepting money to keep quiet.

Four of the 13 people pleaded guilty this week to conspiracy, securities fraud, and commercial bribery. The U.S. Attorney for the Southern District of New York, Michael Garcia, declined to say whether they are cooperating with government investigators.

Prosecutors allege one of the defendants, David Tavdy, bought about17,000 shares of Pepsico last June after a UBS official whose job was reviewing investment upgrades and downgrades, Mitchel Guttenberg, tipped him off that the company would soon upgrade its rating on Pepsico.

A day after making the Pepsico purchase, Mr. Tavdy then sold the shares for a $10,000 profit, and prosecutors say Mr. Guttenberg accepted bribes in exchange for the insider information.

Companies whose securities were traded illegally, according to prosecutors, include a software company, Adobe, a health care company, UnitedHealth Group, and an equipment manufacturer, Caterpillar.

“This didn’t occur in obscure boiler rooms, but rather at top-tier Wall Street firms,” the SEC’s enforcement director, Linda Thomsen, said yesterday.

To hide the scheme, Mr. Garcia said, the participants traded in cash, met covertly at the Oyster Bar in Lower Grand Central Terminal, and communicated with one another using secret codes and disposable cell phones.

Authorities called the plot — which involved a wide-range of Wall Street officials, such as compliance officers, attorneys, and portfolio directors — one of the worst they’ve seen since the corporate scandals that rocked Wall Street in the 1980s.

“In the short run,” an acting special-agent-in-charge of the FBI’s criminal division, Teresa Carlson, said, “crime did pay for these defendants. In the long run, not so much.”

The firms whose now former employees and executives were involved in the alleged insider-training plot, UBS and Morgan Stanley, both said they were cooperating with investigators.

Mr. Garcia said that the firms were unwitting victims of the defendants and didn’t appear to have known about their actions. The defendants were being arraigned yesterday. Mr. Guttenberg, the former UBS client manager and executive director, pleaded not guilty yesterday and was posting $500,000 bail, the Associated Press reported.