Southampton are entitled to 10 per cent of the profit Arsenal have made from selling Alex Oxlade-Chamberlain to Liverpool.
The Gunners paid £12million for the midfielder and sold him to the Reds for £40million.
That means Arsenal’s profit is £28million and the amount due to Southampton is £2.8million.
Speaking about his new signing, Liverpool manager Jurgen Klopp said: “I am really, really happy we have got Alex signed.
“I hear a lot of talk about positions but let’s talk about the player; he is someone with really good abilities who always gives everything for his team. A player that is positive and willing to take risks to try and make positive things happen.
“He may still be young but he has a lot of experience in the Premier League, Champions League and for his country. Already he is a very, very good player and I think he has the mentality and desire to get even better - and that excites me.
Oxlade-Chamberlain signed a five-year deal with Liverpool after rejecting contract offers from Arsenal and Chelsea.