Clubs using the sell-on clause for one of their players normally accept a lower base price for the player in exchange for a percentage of the profits for any future transfers. Let's say that a player named Ristiano Cronaldo is sold from some non-league Portuguese team for an extremely cheap price, but with a 25% sell-on clause included in that transfer deal. Then a giant like Real Madrid, Manchester United or Juventus come in and offer a world record deal for him. That non-league club will be entitled to 25% of that transfer fee. Some of the more recent high-profile sell-on clauses amongst Europe's top 5 leagues include Angel di Maria's move to PSG (giving £5 million to former club Real Madrid), Raheem Sterling to Manchester City (giving £8 million to Queen's Park Rangers) and Cesc Fabergas (from Barcelona to Chelsea, giving Arsenal £5.6 million). Of course, clubs can't see into the future and might miss out on one of these chances. One of the most high-profile cases of missing a potentially profitable sell-on clause was when Southampton waived the sell-on clause for Gareth Bale to Tottenham, who would then go on to move to Real Madrid for £86 million.
The sell-on clause can make quite a lot of money if used on the correct players. Knowing which players those are can make the difference between a club surviving or even thriving.
