West Brom have signed West Ham winger Grady Diangana for a fee of £18m.
The 22-year-old spent last season on loan at The Hawthorns, helping them clinch promotion to the Premier League.
The former England Under-21 international made 21 appearances for the Hammers after coming through the club’s academy.
A West Ham statement said the decision to sell Diangana was made “reluctantly but, ultimately in the best interests of the club”.
They added: “The money received for Grady will be reinvested entirely in the team, in line with the manager’s targets.
“We believe that this will give us the best possible chance of ensuring we have a balanced squad to compete in the Premier League and capable of reaching our objectives and ambitions this season.”