The Gelsenkirchen side opted against keeping the defender on a permanent deal as his loan spell finishes, but did sign Yevhen Konoplyanka
Holger Badstuber has failed to earn a permanent contract at Schalke and could become a free agent if Bayern Munich do not offer the Germany international a new deal.
Badstuber has made 10 Bundesliga appearances since joining Schalke on loan in January, as he continues the long road back from four successive seasons wrecked by a string of injuries which have plagued much of his senior career.
Reports have suggested Badstuber agreed a one-year contract extension with the Bundesliga champions before departing for Veltins-Arena.