And while Portsnouth have been slow to get off the mark in January, a host of their rivals have wasted no time in adding to their ranks with some eye-catching deals.
Scroll down and click through the pages to see EVERY deal done in League One this month:
9. Fleetwood Town
In: Callum Connolly (Everton - loan), Glenn Whelan (Hearts), Lewie Coyle (Leeds United) | Out: Peter Clarke (Tranmere Rovers), Nathan Sheron (Walsall - loan) Photo: Alex Livesey
10. Gillingham
In: Jordan Roberts (Ipswich Town - loan), John Akinde (Lincoln City) | Out: Mark Marshall (Northampton Town), Ousseynou Cisse (Leyton Orient - loan) Photo: Jack Thomas
11. Ipswich Town
In: Josh Earl (Preston North End - loan) | Out: Jordan Roberts (Gillingham - loan), Bartosz Bialkowski (Millwall), Idris El Mizouni (Cambridge United - loan), Toto Nsiala (Bolton Wanderers - loan) Photo: Stephen Pond
12. Lincoln City
In: Tom Hopper (Southend United), Conor Coventry (West Ham United - loan), Tayo Edun (Fulham), Tyreece John-Jules (Arsenal - loan), Max Melbourne (West Brom) | Out: John Akinde (Gillingham), Harry Toffolo (Huddersfield Town), Michael O’Connor (Salford City), Bruno Andrade (Salford City) Photo: Laurence Griffiths