Wolves then responded by recalling nine of the players that had been in action at White Hart Lane for the next league game at home to fellow strugglers Burnley - and won 2-0.
The Premier League said in a statement: "The Premier League Board has issued Wolverhampton Wanderers FC with a suspended £25,000 fine after deciding that the team fielded in their league fixture against Manchester United on 15 December 2009 was not full strength and therefore in breach of Rule E20.
"The board also deemed that the club had failed to fulfil its obligations to the league and other clubs in the utmost good faith and was therefore in breach of Rule B13.
"The board considered submissions from Wolverhampton Wanderers FC and had sympathy for the explanation submitted by the club in relation to similar cases from previous seasons. However the board ruled that this case could be differentiated from the other matches cited and that disciplinary action was warranted."
McCarthy said: "I accept the Premier League's decision. It was never my intention to break any of the Premier League's rules, only to pick a team that was in the best position to get a result. I'm pleased the matter is now closed."
The Premier League statement added: "In coming to this decision the board also wants to put clubs on notice that any future rule breach of this nature would be subject to a disciplinary commission that would have available a full range of sanctions."