UK asset manager Threadneedle called in police last year after its internal systems blocked a suspicious trade worth $150 million.
According to the Financial Times, the firm's controls were triggered by a suspect trade linked to Argentine warrants in August. City of London police and regulators were notified and a junior trader at Threadneedle's investment arm was fired.
Says a brief statement: "In August 2011, our systems stopped a suspicious attempted trade. The matter was immediately reported to the authorities and the individual involved was subsequently dismissed."
Bank risk systems have come under scrutiny in recent years for failing to spot rogue trades.
Regulators in the UK and Switzerland are currently investigating the controls in place at UBS after a rogue trader racked up $2.3 billion through unauthorised trading activity last year. The trader accused of making the loss, Kweku Adoboli is set to face a trial in September.
Back in 2008, Société Général's Jérome Kerviel managed to clock up EUR4.9 billion in losses for which he was later sentenced to five years in jail, two of them suspended.