Manchester United have made just £50million from selling home-grown talent in the last seven years - putting them only eighth on the list of English clubs.
The 2018 transfer of goalkeeper Sam Johnstone, for £6.5m to West Brom, was their most expensive departure, according to a new study released by the CIES Football Observatory.
Chelsea have collected the most money out of Premier League sides - at £175m - while Portuguese giants Benfica are way out in front worldwide at £316m, with over one-third of that coming from the sale of Joao Felix to Atletico Madrid in 2019.