Details of the report were published in the Sunday Telegraph last week. Despite Guinness's assurance that the report was a routine corporate finance exercise and that no bid was under consideration, Grand Metropolitan's shares still rose 18p last Monday in frenetic trading that saw nearly nine million shares change hands.
Attempts by Guinness and Lazards to identify who leaked the document have been thwarted by the Sunday Telegraph, which has destroyed the report.
It has been suggested that the report was leaked by a disgruntled Lazards employee. However, there are now fears that the newspaper may have been unwittingly used by the leaker as a means of getting the price sensitive contents of the Lazards report into the public domain.
The Stock Exchange would not comment officially other than to say that it routinely examines trading in shares where there has been unusual share-price movements. However, sources familiar with the investigation confirmed that the surveillance department was ex- amining trading in Grand Metropolitan shares.
The investigation is focusing on the two-week period between the meeting between the Guinness corporate finance team and Lazards to discuss their analysis and the Sunday Telegraph report last week. In that period, Grand Metropolitan shares rose in value by over 6 per cent.