Saints have scored a moral victory after Aston Villa were found guilty of making an illegal approach for James Beattie.
Villa boss David O'Leary was quoted as saying that Beattie wanted to join his side last August.
The striker went nowhere but turned down a move to Villa Park to switch to Everton for £6.5m earlier this month.
An FA commission yesterday reached its verdict after hearing evidence from Saints chairman Rupert Lowe as well as Villa's representatives.
The FA Premier League reprimanded the club but chose not to fine them.
O'Leary, right, attended a Premier League hearing yesterday to answer the charge, which was brought after he was quoted last summer as saying "there is a player there who wants to join us."
The manager argued he was only responding to press questions after Saints had made it known Beattie was available for sale, but that defence failed.
Villa were handed the punishment following a hearing that lasted almost six hours at the Premier League's headquarters.
Aston Villa spokesman Phil Mepham said: "We are disappointed. We had a fair hearing but the commission said to us that there were mitigating and exceptional circumstances in the case and as a consequence they have given us the lowest possible punishment of a reprimand.
"We accept it and move on."
Saints rejected a £6million bid in August from Villa for Beattie and, although accepting a similar offer this month, the player opted instead to join Everton.
Privately O'Leary was unhappy with the verdict because he had protested his innocence ever since the Premier League charged him over his alleged approach to the striker.
The Villa manager had previously labelled the charge a "farce" and a "disgrace" for comments he made to the media in a post-match press conference at Villa Park on the opening day of the season.
O'Leary had said before the meeting: "We don't think we have done anything wrong. We responded quite rightly after the Southampton game. We were asked if we were interested in a signing and we had to give comments back on it.
"For me to be on a charge for something like this, when I see what goes on in the game, is an absolute disgrace. It is an absolute farce, when you read and see what is in the paper every day, to be charged."
These cases are a rarity and when Middlesbrough accused Liverpool of 'tapping up' Christian Ziege five years ago before his move to Anfield, the Merseysiders were fined £20,000.
Lowe left the hearing without comment but later told Saints' website: "This was a league issue rather than a Southampton one. We complained to the Premier League and they took up the case. We merely acted as a witness on their behalf.
"There is no malice between the clubs and we bear them no ill-will."
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