Names including Kyle Joseph, Aaron Collins and Matt Butcher have all been thrown into the rumour mill, alongside long-term targets Kyle Wootton and Will Boyle.
Danny Cowley has continued to pursue deals for Hayden Carter and 2021-22 top-scorer George Hirst to return to Fratton Park following their successful loans last term.
Meanwhile, as the transfer window ticks on, a number of those 25 names have found new homes away from Fratton Park.
Indeed, 11 have found themselves alternative destinations or signed new deals to stay at their respective clubs.
We’ve taken a look at where those names have ended up since their links to PO4.
1. Matt Butcher - Plymouth
The 25-year-old was strongly linked with a return to Fratton Park with Cowley interested in signing the Portsmouth-born midfielder. The Bournemouth academy star failed to agree new terms at Accrington and caught the attention of the Blues, Bristol Rovers, Bradford, Fleetwood and Plymouth. Argyle won the race for the central midfielder, who penned a two-year deal at Home Park.
Photo: Lewis Storey
2. Kyle Wootton - Stockport
The striker had been a long-term target of the Blues after it emerged Cowley was an admirer of the 25-year-old back in November. Pompey reignited their interest in the forward when his contract at Notts County came to a close at the end of the season. Wootton instead chose League Two outfit Stockport as his next destination despite being interested in a move to Fratton Park.
Photo: Laurence Griffiths
3. Tom Bayliss - Shrewsbury
The News understood in May that Cowley was a fan of the 23-year-old talent, who had been transfer-listed by Preston. The Blues boss eyed the midfielder as one of the solutions to his engine room following Shaun Williams’ exit at the end of the season. Despite rivalling Ipswich, the former Coventry ace made the surprise switch to Shrewsbury on Monday after terminating his contract at Deepdale.
Photo: Lewis Storey
4. Danny Hylton - Northampton
The 33-year-old was recently linked with the Blues with his future at Luton looking increasingly uncertain. However, that rumour was shut down before it even picked up pace with Cowley denying reports they were keen on a swoop. The striker went on to sign a two-year contract with Northampton.
Photo: Pete Norton