Investment banker Thomas Ammann has pleaded guilty to two counts of insider dealing and two counts of encouraging insider dealing, while two women, both claiming to be his girlfriend, were acquitted.
In a trial at Southwark Crown Court it was heard that Ammann passed information to Christina Weckwerth and Jessica Mang and encouraged them to trade in shares of Océ prior to an acquisition being announced.
Both considered Ammann to be their boyfriend and had no idea of the other's existence, the court was told.
After the Océ acquisition was announced, both Weckwerth and Mang sold their shares for a substantial profit. Weckwerth made €1 million (£800,000) and Mang £29,000, and both shared half their profits with Ammann.
According to the Financial Services Authority (FSA), which brought the case, Ammann was an investment banker working at Mizuho International.
In late 2008 and 2009 Mizuho was advising Canon, the multi-national technology company, on its acquisition of Océ, a medium sized Dutch company making photocopiers, scanners, related software and accessories.
The FSA said Ammann was one of the very small team at the bank working on the acquisition and had access to inside price sensitive information.
Ammann will be sentenced at a later date.