Here, AFP Sport looks at the 10 biggest transfers involving English top-flight clubs to have take place over the course of the month:
MARIO BALOTELLI (ITA)
Manchester City to AC Milan (ITA); £19 million ($30.1 million; 22.2 million euros)
- After two and a half controversy-strewn years at Manchester City, Italian striker Mario Balotelli returned to his homeland to join Serie A giants AC Milan on a four-and-a-half-year contract.
CHRISTOPHER SAMBA (CGO)
Anzhi Makhachkala (RUS) to Queens Park Rangers; £12.5 million
- QPR broke their transfer record for the second time in a month to sign former Blackburn Rovers centre-back Samba, having previously spent a reported fee of £8 million to take French striker Loic Remy from Marseille.
DANIEL STURRIDGE (ENG)
Chelsea to Liverpool; undisclosed, reported to be £12 million
- Having fallen down the pecking order at Chelsea, Sturridge jumped ship to join Brendan Rodgers' rebuilding project at Premier League rivals Liverpool.
WILFRIED ZAHA (ENG)
Crystal Palace to Manchester United; £10 million rising to £15 million
- Ivory Coast-born forward Zaha became one of the hottest properties in English football after making his England debut in a friendly in Sweden in November. The 20-year-old elected to join Manchester United, who promptly loaned him back to second-tier Crystal Palace until the end of the season.
PHILIPPE COUTINHO (BRA)
Inter Milan (ITA) to Liverpool; £8.5 million
- Brazil international attacking midfielder Coutinho pitched up at Anfield after failing to make an impact at Inter Milan following a 2010 move from Vasco da Gama. Liverpool manager Brendan Rodgers described him as "a wonderful talent and a great technician".
DEMBA BA (SEN)
Newcastle United to Chelsea; £7 million
- A reported £7 million release clause in Ba's contract meant Newcastle were powerless to prevent him from leaving and it was European champions Chelsea who pounced to take the Senegal striker to Stamford Bridge.
DANNY GRAHAM (ENG)
Swansea City to Sunderland; £5 million
- A key figure as Swansea made a successful start to life in the Premier League by finishing in 11th place last season, Graham opted to join Sunderland after losing his place in the Swans' first XI to close-season signing Michu.
MAPOU YANGA-MBIWA (FRA)
Montpellier (FRA) to Newcastle United; undisclosed, reported to be £6.7 million
- One of five French players to join Newcastle in January, Yanga-Mbiwa arrived after captaining Montpellier to the Ligue 1 title and breaking into Didier Deschamps' France squad.
LEWIS HOLTBY (GER)
Schalke 04 (GER) to Tottenham Hotspur; undisclosed, reported to be £1.5 million
- Holtby, who has a British father, had agreed to join Tottenham at the end of the season, only for Spurs to push the move through ahead of schedule.
JOE COLE (ENG)
Liverpool to West Ham United; free
- Out of favour at Liverpool, 31-year-old Cole returned to his roots by joining his formative club West Ham on a free transfer.