Shaw's contract expires next year, according to The Sun. Hall is understood to want out of Newcastle amid the club's turmoil following Eddie Howe's departure, with sources suggesting he felt a positional switch late last season cost him a place in England's World Cup squad; he was deployed at right-back under Howe before being left out of Thomas Tuchel's squad.
Manchester United have made contact with those close to the player, according to reports, and Hall is said to view Old Trafford as an appealing next step, in part for the chance to play Champions League football again. Chelsea, where Hall began his career before joining Newcastle United, are also monitoring the situation and could look to bring him back to Stamford Bridge.
Newcastle have already sold Anthony Gordon and Sandro Tonali for a combined £170 million this summer, and Arsenal remain keen on captain Bruno Guimarães, adding to the sense of upheaval at St James' Park.
Hall remains under contract at Newcastle until 2029, and his valuation varies significantly across reports, ranging from around £34m to as much as £70m. Whether Hall can be persuaded to stay may depend heavily on who succeeds Howe, with Newcastle not known for selling to United — the two clubs have not done business since Andy Cole's British record £7m move to Old Trafford in January 1995.
United are looking to add a left-sided player generally and are prepared to cash in on teenage full-back Harry Amass to help fund further business, as the club continues to reshape its options behind the ageing Shaw.
Hall made his senior breakthrough at Chelsea before moving to Newcastle, where he has established himself as a regular in Eddie Howe's side over the past two seasons, featuring in the Champions League as the Magpies returned to Europe's top competition.
Journalist Andy Mitten has previously said United's interest in Hall is genuine rather than speculative, noting the club would not be tracking a player unless they believed he wanted to join, while other reports have suggested United and Hall's representatives have already held active talks over a potential move this summer.