Manchester United's current squad is the costliest ever assembled, at a total of €718 million (£628m), according to research by the CIES Football Observatory.
The study analysed the transfers fees paid to assemble current squads from Europe's five biggest leagues.
Paul Pogba, Henrikh Mkhitaryan and Eric Bailly were all brought in from other clubs for fees over the summer, while Zlatan Ibrahimovic was a free agent.
Their additions mean United's squad is €185m more expensive than it was last season.
On the list of most expensive current squads, first-placed United are followed by Real Madrid (€634m), Manchester City (€611m) and Barcelona (€485m).
The Premier League has by far the most teams in the top 20, with nine clubs represented, including Chelsea, Arsenal, Liverpool, Tottenham Hotspur, Everton, West Ham United and Southampton.
Serie A has four and La Liga has three while the Bundesliga and Ligue 1 each have two.
Discussing the data, the CIES Football Observatory reported: "Generally speaking, the correlation between the squad cost and the final position in the domestic league table is very high. However, last season, Leicester City won the English Premier League title with the 17th costliest squad out of 20."