Sunderland manager Roy Keane is still aiming for one more summer signing [GALLO/GETTY]
West Ham's defender Anton Ferdinand joined Sunderland on a four-year deal becoming manager Roy Keane's ninth signing of the summer in the English Premier League.
No financial details were given, although speculation put a price tag of $14.76 million on the 23-year-old England under-21 defender.
"We needed to strengthen our defence and Anton is a great signing," Keane told the premier league club's website.
"He's still young but he has over 160 games under his belt so he has experience, he's learning his trade."
Ferdinand, brother of Manchester United and England defender Rio Ferdinand and cousin of former England international forward Les, had been at West Ham since he was a schoolboy.
Time for change
"It was hard leaving West Ham because I have been there for 16 years but after meeting Roy Keane I knew it was time for a change," said the defender.
Ferdinand is recovering from a hamstring strain but the club website said he was expected to make his club debut at Wigan on Sept. 13.
West Ham said they had accepted the bid in the best interests of the club after failing to reach agreement on a new long-term contract.
Ferdinand had two years remaining on his existing deal.
Keane's signings since the end of last season include Pascal Chimbonda, Steed Malbranque and Teemu Tainio from Tottenham Hotspur, El Hadji Diouf from Bolton Wanderers and Djibril Cisse on loan from Olympique Marseille.
With five days remaining before the end of the transfer window, the manager said he was not done yet.
"I have one more player in mind and then that is the end of it for a few months at least," he said.