The spending of Premier League clubs in January accounted for 51 per cent of transfer fees paid out by Europe's top five leagues, according to a CIES study.
CIES said "the total estimated spending was over one billion euros" in England, France, Germany, Italy and Spain.
Premier League sides had an outlay of £483 million (545 million euros) with a net loss of £100 million (113 million euros).
There was a deficit despite Philippe Coutinho moving to Barcelona from Liverpool for £142 million.
Striker Diego Costa also left Chelsea to join Atletico Madrid for a fee CIES put down as £58.5 million (66 million euros).
Those two moves contributed to La Liga having a record deficit of £166.5 million (188 million euros), says BBC.
The two biggest signings in England involved Liverpool bringing in defender Virgil van Dijk from Southampton for £75 million and Arsenal's purchase of striker Pierre-Emerick Aubameyang for £56 million.
The "estimated balance sheets" of the other leagues saw Italy's Serie A (£42.5 million), Germany's Bundesliga (£29.2 million) and France's Ligue 1 (£12.4 million) in credit.
Premier League clubs spent £430 million in January, according to analysis by Deloitte's Sports Business Group.