Paris Saint-Germain, Manchester City, Manchester United, AC Milan, Barcelona and Chelsea all have huge negative 'balance' figures in excess of -€100m in the last two transfer windows (Summer 2017 & January 2018), according to research from the CIES Football Observatory.
The likes of Borussia Dortmund, Real Madrid and Liverpool, on the other hand, have all made transfer profits after bringing in more money through player sales than they have spent.
Taking into account the world record €222m spent on Neymar last summer, as well as the €180m committed to the permanent signing of Kylian Mbappe, PSG's expenditure for the two most recent transfer windows stands at a mind blowing €418m.
The French giants have sold just €107m worth of players in the same period, giving them a net spend of €311m. In a similar vein, Manchester City's net spend is €246m, while Manchester United's spending against €11m of transfer window income sees their net spend at €186m.
At least PSG, City and United are seeing results on the pitch. AC Milan, who reportedly face UEFA sanctions over their recent financial records, have a net spend of €184m but are languishing in eighth place in the Serie A table despite their big spending.
The net spend for Barcelona for the last two transfer windows stands at €170m, although it must be stated that they have raised significant funds (€244m) through player sales to at least partially compensate for huge deals for Ousmane Dembele and Philippe Coutinho.
Chelsea have spent around €301m on new players in the last two windows, but again, their sales of €200m mean that their net spend for the period in question is much less at €101m.
Perhaps a sign of the level of cash flowing into the Premier League, as many as 10 of the clubs in Europe's top five league with the 'most negative balance' are from England's top flight, with Everton, Brighton, Watford, Huddersfield, Crystal Palace, Newcastle and Leicester all spending at least €45m more than they have brought in.
The club from Europe's top five leagues most 'in the black' for the last two transfer windows is Monaco, raising €416m through player sales and spending just €130m for a €286m profit. No other side even comes close, although Dortmund have a positive transfer balance of €168m.
Real Madrid are surprisingly the sixth most profitable club when it comes to net spend, splashing out €92m on players against €139m received and pocketing €47m as a result.
Liverpool's vast expenditure, including a word record fee for a defender on Virgil van Dijk, was dwarfed by transfer income inflated by Philippe Coutinho joining Barcelona. The Reds are therefore €25m in profit for the last two transfer windows.
Other money savvy clubs include Lyon, Roma, Fiorentina, Sampdoria and Bayer Leverkusen.