In a joint operation with City of London Police, the regulator has also executed search warrants at a number of properties in the Greater London area.
Around 25 FSA staff had been involved in the raids, alongside 11 officers from the City of London constabulary, the watchdog said.
The FSA added that the ongoing investigation is part of a wider crackdown on market abuse.
In a separate insider trading case brought by the FSA, a lawyer was jailed for eight months after being found guilty of passing confidential information to his father-in-law, who used it to trade on shares in the technology firm TTP Communications.
Christopher McQuoid, then the company's general counsel, told James William Melbourne that Motorola were planning a bid for TTP in May 2006.
Mr Melbourne bought 153,824 TTP shares two days before the deal went public and made a profit of Â£48,919.20 ($70,434.76). He and Mr McQuoid split the proceeds.
The case was the FSA's first criminal prosecution of insider trading, the Financial Times noted.