However, they could soon be overtaken by an emerging source in Saudi Arabia.
The summer window began with a normal feel as Real Madrid showed they've still got it with a what could rise to be a British-record £115million fee paid to Borussia Dortmund for Jude Bellingham.
Newcastle's big spending continued as expected with the arrival of £60m Sandro Tonali from AC Milan, while Liverpool also made moves to repair their midfield like many predicted.
Mikel Arteta's Gunners then started making splashes, following up the arrival of Kai Havertz from Chelsea with Jurrien Timber from Ajax, and then the deal of all deals, breaking their transfer record for Declan Rice.
All of that came to a whopping £197m, according to transfermarkt, but their world-leading spend is already under threat.
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And for once it's not the usual suspects. No, we aren't talking about Madrid landing Kylian Mbappe, or Chelsea overindulging under Todd Boehly, but the Saudi takeover.
Everyone laughed at Cristiano Ronaldo for saying the Saudi Pro League could be in the top five in the world after he joined Al Nassr, but in one sense it's already there.
With teams across the gulf state already spending big, news of the Saudi Public Investment Fund taking control of the four biggest clubs in June only accelerated the process.
Reigning champions Al Ittihad made their mark by snagging France stars Karim Benzema and N'Golo Kante, as well as Brazil midfielder Fabinho from Liverpool.
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Another team in the quartet, Al Ahli, now boast a Champions League level front-line of Allan Saint-Maximin, Roberto Firmino and Riyad Mahrez.
Ronaldo's Al Nassr continue to spend, with Sadio Mane on his way, but the fourth side in the group is in a whole different financial bracket.
Al Hilal, who battled Inter Miami for Lionel Messi's services but lost out, have since responded with a vengeance.
Bringing in Kalidou Koulibaly from Chelsea was a boost, but nothing out of the ordinary for the summer of 2023, but what they've done next has changed the game.
Breaking the league's transfer record for Ruben Neves from Wolves for £47m, they added another international calibre midfielder in Sergej Milinkovic-Savic for £34m shortly after, and both players are still in their prime.
Now they've smashed the league's record again, with former Barcelona winger Malcom arriving from Zenit St. Petersburg for £52m.
That takes the team's spending up to £152m for the summer, second behind Arsenal of worldwide teams.
And on top of that, Marco Verratti's impending arrival will likely put them top, while a reported £120m offer for Napoli's Victor Osimhen could take things stratospheric.
That's without even mentioning a failed move for Mbappe which would have destroyed all records after an eye-watering £260m offer.
Coached by former Benfica and Sporting manager Jorge Jesus, the Portuguese great has rarely had a better squad to work with.
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One of the most famous footballing figures back home alongside Ronaldo, the pair would have both hoped to one day see their Primeira Liga compete with Europe's top divisions.
Now though, they're instead at the helm in Saudi, battling the elite by means that were unimaginable just a year ago.