West Ham have signed Swiss midfielder Edimilson Fernandes from FC Sion for an undisclosed fee, reported to be £5m.
The 20-year-old, who scored six goals in 65 games for the Swiss club, has agreed a four-year contract.
He is the fourth midfielder to join the Hammers since the end of last season, after Havard Nordtveit, Sofiane Feghouli and Gokhan Tore.
Fernandes is the cousin of former Manchester City midfielder Gelson Fernandes.