Asset manager Threadneedle, based in the City of London, has said its systems successfully caught a junior rogue employee who attempted to make a suspected $150 million (£95 million) rogue trade.
The issue occurred last August, and Threadneedle has said it alerted authorities and dismissed the alleged rogue trader, who has not been named.
The City of London Police is now investigating the incident, alongside other authorities thought to include financial regulator the FSA. The trade was reportedly around Argentine financial products.
IT systems, alongside management, are often the focus of attention when rogue trading events are reported - financial firms are expected to have the infrastructure in place to effectively monitor traders and identify suspicious activities.
Recent multibillion pound alleged rogue trades at UBS and rogue trades at Societe Generale had prompted concerns that many banks did not have effective enough monitoring and behaviour detection software in place, to aid management.
Threadneedle, which manages around $60 billion of assets, said: "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."
It said no client money had been lost and the trade did not go ahead.