NEW YORK >> A former U.S. congressman from Indiana, technology company executives, a man training to be an FBI agent, and an investment banker were among nine people charged in four separate and unrelated insider trading schemes revealed today with the unsealing of indictments in New York City.

It was one of the most significant attacks by law enforcement on insider trading in a decade, and a prosecutor and other federal officials pledged fresh enthusiasm for similar prosecutions in the future. They said the cheating resulted in millions of dollars of illegal profits for defendants situated on both coasts and in middle America.

U.S. Attorney Damian Williams told a news conference that the cases, in addition to several other recently announced crackdowns on insider trading, represent a follow through on his pledge to be “relentless in rooting out crime in our financial markets.”

“We have zero tolerance, zero tolerance for cheating in our markets,” said Gurbir S. Grewal, director of the SEC Enforcement Division.

An indictment identified Stephen Buyer as someone who misappropriated secrets he learned as a consultant to make $350,000 illegally. Buyer served on committees with oversight over the telecommunications industry while a Republican congressman from 1993 through 2011, the indictment said.

Buyer, arrested today in Indiana, was accused in court papers of engaging in insider trading during a merger of T-Mobile and Sprint, among other deals. Documents said he leveraged his work as a consultant and lobbyist to make illegal profits.

His lawyer, Andrew Goldstein, said in a statement: “Congressman Buyer is innocent. His stock trades were lawful. He looks forward to being quickly vindicated.”

In a civil case brought by the Securities and Exchange Commission in Manhattan federal court against Buyer, he was described as making purchases of Sprint securities in March 2018 just a day after attending a golf outing with a T-Mobile executive who told him about the company’s then-nonpublic plan to acquire Sprint.

“When insiders like Buyer — an attorney, a former prosecutor, and a retired Congressman — monetize their access to material, nonpublic information, as alleged in this case, they not only violate the federal securities laws, but also undermine public trust and confidence in the fairness of our markets,” Grewal said.

He told the news conference that the arrests were not only meant to send a signal to financial industry professionals to protect secrets and follow the law, but also were “intended to send an equally strong message to the investing public” that regulators and law enforcement were focusing on keeping the markets clean.

In a second prosecution, three executives at Silicon Valley technology companies were charged with trading on inside information about corporate mergers that one of them learned about from his employer.

In a third case, a man who was training to be an FBI agent allegedly stole inside information from his then-girlfriend who was working at a major Washington D.C. law firm. According to court papers, he and a friend made more than $1.4 million in illegal profits after he learned that Merck & Co. was going to acquire Pandion Therapeutics.

In a fourth indictment, an investment banker based in New York was charged with sharing secrets about potential mergers with another with an understanding that the pair would share illegal profits of about $280,000.