That’s because the Blackburn Rovers loanee’s deal at Ewood Park still has two-and-a-half years remaining, presenting Danny Cowley with a hefty fee to fork out IF Tony Mowbray decided to let the defender leave at the season’s end.
So what are the alternatives if Carter’s Fratton Park stay remains a short-term one?
Here’s 18 viable centre-back options across the Championship and League One whose contracts expire in June.
1. Tom Holmes - Reading
Age: 21
2021-22 appearances: 26
Clean sheets: 1
Picture: Ryan Pierse/Getty Images Photo: Ryan Pierse
2. Aapo Halme - Barnsley
Age: 23
2021-22 appearances: 7
Clean sheets: 2
Picture: Catherine Ivill/Getty Images Photo: Catherine Ivill
3. Gabriel Osho - Luton Town
Age: 23
2021-22 appearances: 25
Clean sheets: 8
Picture: Marc Atkins/Getty Images Photo: Marc Atkins
4. Eiran Cashin - Derby County
Age: 21
2021-22 appearances: 8
Clean sheets: 4
Picture: Alex Pantling/Getty Images Photo: Alex Pantling