Jose Mourinho sealed deals for Kurt Zouma, Mohamed Salah and Nemanja Matic - with the French defender sent back out on loan to Saint-Etienne - but the Blues in fact recorded a profit for the window thanks to the sales of Kevin De Bruyne and Juan Mata.
The Spaniard's record-breaking arrival at Manchester United puts the reigning English champions second in our list, with David Moyes splashing €44.73m on the 25-year-old as he looks to revitalise his side's ailing campaign. French champions Paris Saint-Germain are some way behind in third, with the sole capture of Yohan Cabaye still enough to place them high on the list.
Inter were the big spenders from Serie A this month as their late deal for Lazio's Hernanes puts them fourth, while Galatasaray's busy window saw them complete seven signings for just over €18m - slightly ahead of Russian side Zenit St Petersburg, who forked out the majority of their outlay on Jose Salomon Rondon.
Wolfsburg were the busiest side in the Bundesliga and find their way into seventh in our list, just ahead of Hull City, who splashed out on the double signing of Nikica Jelavic and Shane Long. Fulham also spent big in the window, investing €15.2m in a bid to avoid Premier League relegation - the majority of which was spent on a late move for Kostas Mitroglou - and Monaco complete our top 10.
In total, the Premier League saw by far the biggest spending in the January window, with clubs totalling €139.28m of investment in new players. Ligue 1 is second - though a long way behind - on €54.1, with the Bundesliga third on €31.3m. La Liga's absence from our top 10 is little surprise when you consider only €12.55m was spent on transfer fees in the division for the winter window, with the likes of Barcelona and Real Madrid passing on the opportunity to invest in their squads.
|JANUARY SALES | Top 10 clubs by expenditure
|Gross outlay||Net outlay|