Fox was the subject of several bids from Sheffield Wednesday during the summer transfer window.
The Owls later signed Dutch left-back Urby Emanuelson on a free transfer, but the former AC Milan star is yet to feature for his new club and has been named in just one of Carlos Carvalhal's matchday squads.
Now Owls left-back Urby Emanuelson
And the promotion hopefuls could be in luck, it seems, with Charlton reportedly admitting defeat in their attempt to keep Fox - as well as Everton-bound winger Ademola Lookman - out of the clutches of higher-division clubs.
Charlton Athletic's Morgan Fox
The 23-year-old began his career at the Valley and has to his name 79 Championship appearances.
Wednesday have begun their January business early, bringing in West Bromwich Albion winger Callum McManaman - another reported summer target - on loan until the end of the season.
Should Sheffield Wednesday make Fox move next month?