Luis Marti-Sanchez, who worked at Nomura's London offices, says that his employers breached his contract by failing to pay him the full bonuses he was entitled too.
Having earned Nomura nearly Â£20 million last year, Mr Marti-Sanchez claims he was paid only Â£1.3 million as an annual bonus, and entirely in deferred shares that could be worth even less.
Lawyers representing the former trader say that he was verbally promised on numerous occasions that he would receive at least 20 per cent of the profits gained on trades made personally by him.
Instead Mr Marti-Sanchez was paid the equivalent of only 4.3 per cent.
The case does not appear to be unusual among City banks, with similar cases regularly making it to the courts.
With investment banks heavily reliant on the judgment of individuals for their profits success, many believe that successful traders should be heavily rewarded, although the size of the bonuses being discussed has surprised observers outside of the sector.