The former boss of US phone company Qwest Communications, Joseph Nacchio, has been found guilty of 19 counts of insider trading.
A court in Denver ruled that in 2001, Nacchio sold $50m (£25m) of Qwest stock after being told the firm would miss its financial targets.
Nacchio, who was cleared on 23 charges, faces up to 10 years in jail and a fine that could total $19m.
His lawyer said there would be an appeal against the verdict.
Nacchio, who showed no emotion when the verdict was read out, is now due to be sentenced on 27 July.
Prosecutor Colleen Conry said the Nacchio verdict “sent a message all the way to Wall Street”.
Qwest, the third-largest US regional phone company, became the target of both federal prosecutors and regulators in 2002, after it restated £2.2bn in revenues.
The investigation eventually led to Nacchio’s arrest.
Senior Qwest staff testified in court that Nacchio had tried to hide the firm’s financial difficulties from investors.