According to the regulator, searches were today conducted at business and domestic premises in London and Kent. A 44 year-old man was arrested and interviewed under caution at a London police station, before being released on bail, pending further enquiries.
The action is the latest in a wide-ranging probe conducted by the FSA, in conjunction with the Serious Organised Crime Agency, which began with raids on 16 addresses in London, the south east of England and Oxfordshire, in March 2010.
Six men, including two senior professionals at "leading City institutions" and a hedge fund employee, were arrested on suspicion of being involved in a sophisticated insider dealing ring. A further arrest was made in April 2011 and the probe is described as “ongoing”.
During the past few years, the FSA has sought to demonstrate a tougher line on market abuse. It has secured 11 convictions since March 2009, and is currently prosecuting 16 other individuals for insider dealing.
Earlier this week, the regulator announced that Margaret Cole, credited with leading its deterrence strategy, will leave the organisation at the end of March.
Cole joined the FSA as director of enforcement in July 2005, managing a division of 450 people, with responsibility for enforcement policy, intelligence gathering, forensic investigations, and civil and criminal proceedings, in areas including market abuse and financial crime.
She was appointed to the FSA board as managing director of enforcement and financial crime in September 2010, and later became the first managing director of the conduct business unit.
Cole said: “We have shown the FSA is not afraid to take on difficult cases and will not shy away from pursuing criminal prosecutions, however difficult to prove. It’s painstaking work and the legal process takes a long time but there are people sitting in prison now because of our commitment.
"And the next 12 months will see more trials and more convictions as the pipeline of our cases comes to fruition in the courts.
“It has been a challenging but rewarding few years and I believe, with the help of a team of quality people, I have created a successful enforcement platform to take into the UK’s new regulatory authorities.
"The time has come for me to seek a fresh challenge, knowing that I leave the continuation of a winning strategy in safe hands.”
Note: This article was amended on 17 Feb, 2012.
Update: Legal & General Investment Management confirmed on 17 Feb, 2012 that the arrest on 16 Feb was of an employee at the firm.
A statement from the company read: "With reference to the FSA’s press notice 015/2012 issued 16 February 2012, we can confirm that a 44 year old man employed by Legal & General Investment Management was arrested on 16 February and released on bail pending further enquiries.
"We are not aware of any detriment caused to customers or any impact on our financial results. We are unable to provide any further details at this time."