And that means there are already a host of talented free agents available for clubs like Sunderland to target.
The Black Cats have had some mixed luck in the free agent market in recent years, but could any of these players – who are already available for nothing – prove good recruits?
Scroll down and take a look:
1. Marcus Maddison
We'll start with the name on the lips of all Sunderland fans - Marcus Maddison. The attacking midfielder was released by Peterborough United earlier this week and, having been regularly linked with Sunderland, is a player supporters are keeping a close eye on. Photo: Kate McShane
2. Jonathan Grounds
Formerly of Middlesbrough, Grounds has been allowed to leave Birmingham City. A versatile defender, he would plenty of Championship experience - but has scarcely played senior football this season. Photo: Alex Pantling
3. Jordan Rossiter
Rossiter is currently on loan at Fleetwood Town, but is set to be released by parent club Rangers at the end of his contract. While the Cod Army remain keen on a permanent deal, a host of clubs will no doubt be monitoring the all-action midfielder's situation. Photo: Lynne Cameron
4. Ben Alnwick
Alnwick has been a free agent since leaving Bolton Wanderers last year, and spent time training with the Black Cats earlier this summer. With Jon McLaughlin potentially on the move - could the former Bolton man prove an adequate replacement? Photo: Laurence Griffiths