Atalanta have completed their move for Middlesbrough midfielder Marten de Roon 13 months after selling him to the Teessiders for £12 million.
The fee the Italian club has paid for its former player has not be released under a privacy clause.
De Roon's move was confirmed by Boro in a statement released via their official website, www.mfc.co.uk, on Thursday evening.
Under the headline "Marten de Roon returns to Atalanta,'' it said: "The Dutch midfielder has gone back to play in Italy after just one game in the Championship.
"The move is a permanent one with Atalanta re-signing the player they sold to us a year ago.