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