Birmingham have signed full-back Yan Valery on loan from Southampton and teenage forward Keyendrah Simmonds on a permanent deal from Manchester City.
Valery, 21, has joined the Blues until the end of the season while Simmonds, 19, has agreed a contract until 2023.
The duo join midfielder Rekeem Harper, who has joined on loan from West Brom, and striker Sam Cosgrove, a permanent switch from Aberdeen, as the Blues' additions in January.
Midfield pair Josh McEachran and David Davis both left St Andrew's earlier this month.
The Sky Bet Championship club have also let frontman Miguel Fernandez join Spanish Segunda Division B side CD Guijuelo for the rest of the season.
Fernandez has made just one appearance for Birmingham since moving to the club from UE Cornella in 2019, but he has been a regular in the under-23 side this season, scoring five times in 12 appearances.
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