Manchester United have spent a record £1.19bn more on transfers over the past decade than they have recouped through player sales, according to a new study.
Chelsea are second with a negative net spend of £883m, followed by French side Paris St-Germain with £863m.
Arsenal (£745m) and Manchester City (£732m) complete the top five.
A total of 13 Premier League clubs are in the top 20.
The figures used in the study include fixed transfer fees, fee-paying loans and any add-ons regardless of whether they have actually been paid.
Notable United transfers include the then Premier League record capture of Paul Pogba for £89.