Six men have been convicted over a £1m insider dealing ring at major investment banks, the Financial Services Authority said on Monday.
Ali Mustafa, a print room assistant at UBS, and his brother Ersin, who worked as an operations manager in the confidential print room at JP Morgan Cazenove, stole documents on secret takeovers or mergers and passed them on to five traders, the trial at Southwark Crown Court heard.
Using data obtained from the banks, the men made a profit of more than £1m from trading shares, the court heard.
They passed the information to five traders, Pardip Saini, Paresh Shah, Neten Shah, Bijal Shah and Truptesh Patel, who placed spread bets.
Companies targeted included Reuters, Premier Oil, Vega, Enodis, Thus and Biffa.
They and Ali Mustafa, 31, of Basildon, Essex, were convicted of insider dealing today, the FSA said.
An eighth man, broker Mitesh Shah, 45, from New Barnet, Hertfordshire, was acquitted of insider dealing, the FSA said, while Ersin fled to Northern Cyprus.
The FSA said the case was the longest and most complex prosecution it had brought to date.
Tracey McDermott, acting director of the FSA's enforcement and financial crime division, said its team had worked for several years to bring the men to trial.
"The defendants were involved in a long running, sophisticated and very profitable scheme," she said.
"Indeed, several of the defendants derived the majority of their income from the scheme.
"They took a number of steps to reduce the likelihood of detection and continued, throughout the trial, to deny any wrongdoing.
"This sort of behaviour poses a significant risk to the integrity of markets and cheats honest investors."
Mustafa and co-defendants, Saini, 39, of Plumstead, south east London, Patel, 49, of Wapping, east London, Paresh Shah, 47, of Potters Bar, Hertfordshire, Bijal Shah, 37, of Harrow, west London, and Neten Shah, 49, of Edgware, north London, will be sentenced on Friday.