Shares in U.K. fund manager Gartmore Group Ltd. plummeted more than 30% as the company said it has suspended one of its top portfolio managers, Guillaume Rambourg, but denied that the firm is connected to an insider-dealing investigation by the Financial Services Authority that resulted in seven arrests last week.

The shares were down 53 pence (79 cents), or 31%, at the close of Tuesday's session, at 116 pence.