West Ham swap Savio for Da Costa
The Premier League club have signed former PSV Eindhoven and AS Nancy defender Da Costa, 23, on a three-year contract, they said on their website.
The French-born defender has twice been named in the Portugal squad.
The club will retain 50 percent of his sell-on value after the 20-year-old arrived at the Boleyn Ground in January from Brescia for an undisclosed fee.
"Had our financial situation been different we would have preferred to have kept and developed Savio," said West Ham United chief executive Scott Duxbury.
"However, we are required to make savings and our policy has always been to sell players on the fringes rather than established first-team players.
"With the fee we received for Savio and 50 percent sell-on together with acquiring the highly-rated Da Costa, it represented a great deal."
West Ham had already bought Serie A forwards Luis Jimenez and Alessandro Diamanti from Inter Milan and Livorno respectively in the transfer window.
They have also permanently signed Congo left back Herita Ilunga from Toulouse and Spartak Moscow's Czech Republic midfielder Radoslav Kovac after successful loan deals.