GENEVA (Reuters) - The Swiss Attorney General's office has opened an investigation into possible insider trading in the securities of cement producer Holcim Ltd, the office said in a statement on Sunday.
The investigation was first reported by the NZZ am Sonntag paper, which said suspected insider trading took place just before Holcim's announcement last April of a plan to merge with French rival Lafarge SA.
The investigation is probing a possible offence by a "secondary insider", not someone with authorised access to insider information but who obtained such information in an unauthorised way, the Attorney General's office said.
The statement gave no further details. Holcim did not immediately respond to a request for comment.
The two firms say they are on track to complete the merger in the first half of 2015 following its approval by European Union regulators, who demanded a swathe of asset sales as a condition for the merger.
Reporting by Tom Miles; Editing by Hugh Lawson and Alison Williams