Top 10 for both revealed 

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As we approach the end of the season in Europe’s top leagues, we can begin reflecting on what we have witnessed this campaign. Last summer, clubs splashed out over €9 billion on players – the record spend in a single transfer window. But who has seen the best and worst returns on their investments? To try and quantify this, here at Transfermarkt, we have calculated the summer signings to both gain and lose the most market value since September 2, 2025 – the day after the summer transfer window shut. Let’s begin with the biggest risers.

Summer signings to gain most market value this season

Bundesliga signings dominate the increase list. In first place is RB Leipzig winger Yan Diomande. The Ivorian was signed from Spanish side Leganés for €20m in the summer when his market value was just €1.5m. Nine months on and 22 goal contributions later, that value now stands at €75m, meaning a whopping +€73.5m increase across the course of the season. There has already been reported interest from Premier League clubs. In second is Tottenham centre-half Luka Vuskovic – he signed on loan for German side HSV in the summer when his value was at just €12m – the Croatian’s worth is now €60m after a stellar campaign – a +€48m increase.

Nick Woltemade has seriously struggled at Newcastle of late, and is likely to see his value decrease in the upcoming Premier League update. However, largely due to the fee, as well as his fast start, his value has risen by +€35m since the German made his move to St James’ Park. There has also been a +€35m increase for Bayer Leverkusen striker Christian Kofane. The Premier League trio of Malick Thiaw (+€27m), Bryan Mbeumo (+€25m), and João Pedro (+€25m) make the top 10, as does Real Madrid full-back Álvaro Carreras (+€25m).

Summer signings to lose most market value this season

Now, to the other end of the scale, and the summer signing with the biggest decrease to his market value is none other than Liverpool’s Florian Wirtz. The German had a market value of €140m when the Reds splashed out €125m on his signature, but that value has since fallen to €110m after a disappointing first season at Anfield. In second is another Liverpool signing; the Reds broke the Premier League transfer record to bring in Alexander Isak from Newcastle for €145m, but after a slow start and then an unfortunate injury, his value has dropped from €120m to €100m over the course of the campaign. Tottenham’s Xavi Simons is third after a -€20m drop from €70m to €50m.

Former Liverpool striker Darwin Núñez is fourth after seeing his value drop by -€20m since moving to the Saudi Pro League. Defender Pervis Estupiñán is fifth after seeing his market value decrease by -€16m since moving to AC Milan last summer. Another Liverpool signing is in sixth in Jeremie Frimpong after a -€15m downgrade, whilst new Chelsea winger Jamie Gittens (-€15m) and Arsenal striker Viktor Gyökeres (-€10m) also find themselves in the top 10.