Reserve goalkeeper Aaron Ramsdale has joined Premiership Bournemouth for an undisclosed fee.
Boss Chris Wilder explained: "There's been interest in Aaron for quite a while and despite rejecting smaller offers, this bid was too good to turn down. The bid exceeded the club's valuation.
"We are in the game of winning football matches and being a sustainable business - as we stand Aaron's transfer does not affect our challenge for promotion. Simon Moore is in possession of the goalkeeper's shirt at the moment and in George Long and Jake Eastwood we have adequate cover.
"A number of discussions have taken place since the substantial bid was submitted and we felt agreeing to the sale is the best decision for the club in terms of the initial fee and the associated add-ons. Also, it is opportunity for Aaron that we cannot deny him and we wish him well for the future."
Ramsdale, 18, who has progressed through United's U18s and U23s squads having joined the Blades from Bolton Wanderers, has featured twice this season, both appearances coming in the Emirates FA Cup.
It has been a productive and busy transfer window at Bramall Lane. Samir Carruthers, Daniel Lafferty and James Hanson have penned permanent contracts with United, whilst Ethan Ebanks-Landell, Joe Riley, Jay O'Shea and Harry Chapman will be with the club until the end of the season on loan deals. Meanwhile, Ramsdale's departure sees him join Ben Whiteman (loan) and James Wallace (contract terminated) in leaving the Lane.