As the festive period comes to an end, clubs around the world will be preparing for the upcoming January transfer window.
But they may want to proceed cautiously with their business after a new study revealed peak transfer value collapses from 2024, including for an Arsenal star.
Premier League clubs spent £1.75bn in the summer and leagues such as the Saudi Pro League also spent lucratively, although not all of those deals paid off.
According Transfer marketThe biggest collapse in transfer value, between January 1 and Boxing Day, was suffered by PSG star Randal Kolo Muani.
The Frenchman joined the team in a £76.4m deal from Eintracht Frankfurt in last year's summer transfer window, but his value has now fallen by £33m (€40m).
After starring in the 2022 World Cup with France, Kolo Muani was a highly sought after name in French football. But his performances since arriving at PSG have left a lot to be desired.
Neymar (left) and Leroy Sané (right) are among the stars whose value has fallen dramatically.
PSG striker Randal Kolo Muani has suffered the biggest drop in transfer value this year
An Arsenal star also made the top five for biggest drop in transfer value
The striker has scored just 11 goals in 53 games for PSG this season, just two goals in his first 10 Ligue 1 games.
Just after Kolo Muani on the list are Victor Osimhen and Leroy Sane, who suffered a £29m (€35m) drop in their transfer value.
Nigerian striker Osimhen was the talk of the transfer window this summer after being linked with a move from Napoli to Chelsea.
However, a move to England never materialized and instead, after being excluded from Napoli's squad, he opted for a last-minute loan move to Galatasaray.
German international Sané has seen his playing time reduced at Bayern Munich since the summer arrival of Michael Olise from Crystal Palace.
Since then, Sané has started just five Bundesliga games for Vincent Kompany's side and has managed just three goals in 11 total league appearances.
After Sane and Osimhen are Gabriel Martinelli, Kingsley Coman and Neymar, whose transfer values have reportedly fallen by £25m (€30m).
Arsenal striker Martinelli has been criticized in recent weeks for his poor performances for the title-chasing team.
Arsenal star Gabriel Martinelli has seen his price fall amid difficult performances of late.
Bayern Munich winger Kingsley Coman has suffered the same fate as his teammate Sané
The Brazilian has four goals in his 15 Premier League appearances this year and questions have been raised over whether Arsenal need to invest in a new winger.
Furthermore, Coman has suffered a similar fate to his teammate Sane, who has struggled to earn a starting spot in the Bayern Munich lineup after his summer business.
Meanwhile, Neymar has also suffered a substantial decline in transfer value following his injury problems since moving to Saudi Arabia.
The Brazilian joined Saudi side Al-Hilal in 2023 but has only made seven appearances for the team after being sidelined by injuries.
He recovered from his ACL injury in October, but then suffered another injury during Al-Hilal's Asian Champions League match.
Just outside the top 10 on Transfermarkt's list are the likes of Christopher Nkunku, Jack Grealish, Gabriel Jesus, Evan Ferguson and Kevin de Bruyne.
French striker Nkunku officially joined Chelsea on January 1 in a deal worth £53m, but has since struggled to find a place in their starting line-up.
The 27-year-old has only started two Premier League games for the Blues and mostly only features in their European matches.
Grealish, meanwhile, has endured a difficult year in a Man City shirt as he failed to find the back of the net for the champions throughout 2024.
Victor Osimhen (left) and Frenkie de Jong (right) are also included in the list
Manchester City playmaker Kevin de Bruyne has also seen a significant drop in his transfer value.
Brighton striker Evan Ferguson had been tipped for a big-money move after last season, however the Irish striker has also found himself on the periphery this year.
Like Nkunku, Ferguson has only started two Premier League games in the 2024-25 campaign, scoring just one goal for the Seagulls.
Finally, Kevin de Bruyne has seen a significant drop in value amid a season derailed by the Belgian's injuries. The midfielder was sidelined in October and has struggled to rediscover his best form.
Another surprising name on the list is Barcelona midfielder Frenkie de Jong, whose transfer value was reduced by £16.6 million (€20 million) last year.