Two men and three women have been arrested and four properties were searched by police in the City of London (LSE: CIN.L - news) , Lincolnshire, Leicestershire and North Yorkshire as part of an investigation into insider dealing and market abuse.
The Financial Services Authority (FSA) said on Tuesday that the two men, aged 37 and 62, and three women, aged 39, 51 and 63, were in custody and awaiting questioning by police.
No further details were immediately available, although the regulator said the arrests were not linked to any other ongoing insider dealing investigation.
The FSA has been clamping down on insider trading. It has secured 21 convictions for the offence since 2009.
Insider dealing can carry a jail sentence of up to seven years.