Monaco made an astonishing €289 million in profit from their transfer activity in the last window, with Ligue 1 rivals Paris Saint-Germain the biggest spenders as the world record transfer for Neymar saw the club post highest negative balance at -€343m.
The CIES Football Observatory has released analysis of the transfer activity in Europe's top-five leagues and found Monaco generated €394m in player sales, while only spending €105m of that on replacements.
The Ligue 1 champions allowed Kylian Mbappe, Benjamin Mendy, Tiemoue Bakayoko and Bernardo Silva to leave in lucrative deals.
Monaco's net balance would have been even higher had Thomas Lemar joined Arsenal on deadline day, Arsene Wenger having confirmed the Gunners made a €100m bid.
23 - Mbappé was involved in 23 league goals in 16/17 (15 goals, 8 assists), more than any other U20 player across the European Top 5. Jewel. pic.twitter.com/oP7L6nNrhj— OptaJean (@OptaJean) August 31, 2017
Borussia Dortmund made the second biggest profit from their transfer activity, their dealings generating a positive net figure of €110m with Ousmane Dembele's switch to Barcelona - which could reach a value of €147m - the biggest contributor.
Arsenal also made a profit despite breaking their transfer record to sign Lacazette for €60m. He was the only player they paid a fee for in the window, while they made €86m in sales, boosted by Alex Oxlade-Chamberlain's deadline-day move to Liverpool.
Three Premier League sides also landed among those with the biggest losses, with Manchester United (-€186m), Manchester City (-€173m) and Chelsea (-€106m) all just behind AC Milan on a negative of €189m.
Of the five leagues, La Liga was the only league to make an overall profit on transfer activity.
The Premier League clubs took the biggest losses, splashing out €835m more than they received for players over the course of the window.