The Financial Conduct Authority has arrested a man in Harrogate in connection with insider dealing and market abuse.
The City regulator said it searched the 49-year-old's home in a dawn raid on Thursday carried out with the North Yorkshire and West Yorkshire police forces.
The man was taken into custody for questioning and has not been charged. The arrest is not linked with any of the FCA's other insider dealing investigations and the arrested man did not work in the financial services industry.
The regulator declined to release further details of the case.
The FCA and its predecessor, the Financial Services Authority, have tried to clamp down on market abuse after the FSA was accused of taking a soft line on the crime.
Following adoption of the tougher approach, 23 people have been convicted of insider dealing. The FCA is currently prosecuting seven people for the offence, which is punishable by a fine or up to seven years in prison.
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