A lawyer has pleaded guilty to an insider trading charge in New York City, raising to 20 the number of defendants who've done so in what authorities call the largest hedge fund insider trading case ever.

Jason Goldfarb told a Manhattan federal court judge Thursday he made a "horrible mistake" by agreeing to accept money and arrange for secrets about mergers and acquisitions to be passed to a securities trader.

Goldfarb was among more than two dozen people charged. He pleaded guilty to conspiracy and securities fraud. Sentencing is Aug. 19.

Goldfarb's 2009 arrest came as part of the Galleon Group hedge fund prosecution.

Galleon founder Raj Rajaratnam (rahj rah-juh-RUHT'-nuhm) is on trial now. Prosecutors say the Sri Lanka-born Wall Street heavyweight used "corporate spies" to get rich off inside trades. He insists he was merely a savvy investor.