Sunderland manager Roy Keane has secured the £3m capture of Reading utility player Greg Halford.
Halford played just 181 minutes of football for Reading in three games
Halford had a medical over the weekend and has now signed a four-year contract with the Wearside club.
The move comes as a surprise as the 22-year-old only joined Reading from Colchester in January in a £2m deal.
The fee is for an initial £2.5m, rising to £3m depending on how many appearances he makes for the Black Cats this season.
Sunderland boss Roy Keane said: "I'm delighted Greg has decided to join us, and hopefully he will play a big part in what we hope to be a successful few years for the club."
Halford added: "It's great to be here. The set-up at Sunderland is phenomenal and I can't wait to get going. I've had a taste of the Premiership with Reading and I want more."
Halford, who played as a right-back, midfielder and striker for Colchester, made just three appearances after arriving at the Madejski Stadium as the club's record signing.
Sunderland have pursued the player strongly and I'm sure he will do very well for them
Reading director of football Nicky Hammond
Reading director of football Nicky Hammond said: "It's fair to say that Greg did not make the impact here that both he and ourselves would have liked.
"Sometimes in football, players do move on quite quickly if it's felt that the fit isn't quite right. But this is absolutely no reflection on Greg as a person or a player and he has been a very good professional during his short time with us.
"From a purely financial perspective, this is an excellent deal for us with a good upside on our initial investment in January.
"Sunderland have pursued the player strongly and I'm sure he will do very well for them.
"Everyone at Reading wishes Greg every success for his future."
Halford was part of the Colchester side that got promotion to the Championship in 2005-06.
His form for the U's and the England Under-20 side saw him linked with a number of Premiership clubs, including Manchester United.
Colchester turned down a bid from Sheffield United for him and dismissed his transfer request during last summer.
With his deal set to come to an end this summer Colchester opted to sell him in January.
Halford, who scored 24 goals in 154 games for the U's, was thought to be part of Reading manager Steve Coppell's long-term plans.
However, the club have decided to make a quick profit.
Keane is expected to be busy in the transfer market this summer, with the club vowing to back him with significant funds as they prepare for life in the Premiership.
Defenders are a priority with Danny Simpson and Jonny Evans - a key part of last season's Championship-winning side - both returning to Manchester United after their loans ended.