In Brazil and some other South American nations, players have two parallel deals, one for their playing rights and another for their economic rights.
The first stipulates which team the player plays for, the second who gets what if the player is transferred.
In addition to their clubs, companies, investment funds, the players and their agents can all hold a stake in a player's economic rights.
"The easiest way to understand it is to think of football as you do the stock market, where the players are stocks," said Fabio Buratta, a businessman who has shares in Brazilian players.
"If I think that a young player is promising, I pay the club, say, 50 percent of what they think he is worth and in the future I will get 50 percent of whatever fee he commands. The risk is that the player doesn't make it and I lose my money."
In Oscar's case, 25 percent of his economic rights were held by himself and 25 percent by his agent, according to Internacional. The other 50 percent belonged to the club.
That means half of Chelsea's transfer fee will go to Internacional, with the rest divided between the player and his agent. A small part of Inter's fee will go to Oscar's first club Sao Paulo under a separate sell-on clause.
It was revealed that West Ham did not own the players' contracts and after investigations and court cases the London club was fined £5.5 million.
