By Ameet Sachdev | A Bolingbrook-based provider of physical therapy services has a new investor: GTCR, a Chicago-based private equity firm.

GTCR did not disclose the amount of its investment in ATI Holdings LLC. The capital will come from GTCR Fund IX, a fund with $2.75 billion of committed capital, the firm said Monday.

ATI, founded in 1996, provides rehabilitation services throughout 88 outpatient clinics in Illinois, Wisconsin and three other states.