GI did not disclose the size of Apollo's investment. It said the buyout firm would take two seats on GI's board after the deal is closed, expected in the third quarter this year, but its backing would to be in the form of a "non-control investment."

Spokespeople for the two companies did not immediately respond to requests for comments seeking additional details.

Dealmaking in the healthcare space has picked up in recent months even as rate hikes and inflation pressures dampen corporate appetite for buyouts. Private equity companies have also snapped up stakes, seeking to take advantage of relatively cheaper valuations.

Under the deal, physician owners of GI who already have a 70% ownership in the company will also buy back the minority stake held by investment firm Waud Capital Partners.

GI's physicians operate across 14 U.S. states including Missouri, Mississippi, Oklahoma and Texas.