In the meantime, here's every signing the Black Cats have made in January over the last decade, and a look at where they are now.
13. Bryan Oviedo - January 2017
.He remained with the club despite their descent into League One, and played regularly last season. In the summer, he completed a move to his former club Copenhagen, where he's very much a backup option. (Photo by Nathan Stirk/Getty Images) Photo: Nathan Stirk
14. Darron Gibson - January 2017
After leaving the club in difficult circumstances, the Republic of Ireland international was snapped up by Wigan Athletic. He's now a free agent. (Photo by Ian MacNicol/Getty Images) Photo: Ian MacNicol
15. Kazenga Lualua - January 2018
Released following Sunderland's relegation in the same season he joined, the winger was signed by Luton Town, where he still plays and is a regular starter. (Photo by Stephen Pond/Getty Images) Photo: Stephen Pond
16. Max Power - January 2019
The midfielder joined from Wigan Athletic after impressing during a loan spell, and he's become a regular starter for the Black Cats. (Photo by Alex Davidson/Getty Images) Photo: Alex Davidson