The robberies happened between July 18 and July 27 on Blue Line and Red Line trains and platforms.
Five people have been beaten and robbed on CTA trains and platforms in the Loop since July 18.
In each incident, one to three men threatened and beat CTA passengers, hitting them in the face and body before taking property from their hands and pockets, Chicago police said.
The robberies happened in the afternoon and evening hours:
Anyone with information about these robberies is asked to call Area Central detectives at 312-747-8384.
