Manchester United are being investigated over the way they released news of the possible sale of midfielder David Beckham.
The club announced last Tuesday, via the Press Association, they had accepted a conditional offer for Beckham from Spanish club Barcelona, causing its share price to rise.
But the club did not match that press release with a formal statement through London Stock Exchange channels.
Part of the remit of the Financial Services Authority (FSA) is to ensure developments that can influence a company's share prices are reported promptly direct to financial markets.
The Manchester United spokesman would not comment on the nature of the FSA's investigation.
Manchester United had made a previous announcement about Beckham via its website on Saturday, June 7th, in which it first confirmed that Italian and Spanish soccer clubs were interested in signing the 28-year-old player.
FSA rules state any price sensitive announcement made over a weekend should be formally reported when the market next opens. Manchester United made a statement to the stock exchange about the interest in Beckham shortly after the start of trading on Monday, June 9th.