I’m looking at Transfermakt. In 2016 after their transfer ban, Barcelona lost Neymar. Just as Raul had done well to bring him in (while making off book payments), he got a good £200m off PSG.
But then he went on a spending streak that would make you blush, blowing 2.5x that on players like Coutinho, Dembele, Digne, Turan, Vidal, Gomes, Semedo and Paulinho. Dembele can blame injuries and ill-discipline for failing to pan out but even his purchase fee was at least 50% over valued. And the rest, maybe you can explain where the ROI was in that transfer spree.