Top 50 most expensive transfers this summer by true cost: Isak isn't No. 1

What's the most expensive transfer ever?

It seems obvious: Paris Saint-Germain paid the €222 million release clause to acquire Neymar from Barcelona . The only other player who has come close to that was another player acquired by PSG the same year: Kylian Mbappé , for €180 million, from Monaco. No one else has moved for even €150 million.

But €50 million in 2025 is a lot different from €100 million in 2015, and money spent by PSG is a lot different from money spent by, say, Marseille or Mallorca . In an era where nearly every league and UEFA have spending rules pegged to a certain percentage of team revenue, perhaps there's a better way to compare transfer spending -- across teams and across eras.

If we look at Neymar's transfer as a percentage of PSG's revenue for the 20