 SCOTTSDALE, Ariz., May 25, 2021 GLOBE NEWSWIRE -- The Joint Corp. NASDAQ:JYNT, a national operator, manager, and franchisor of chiropractic clinics, announced the company has been selected by the SP Dow Jones Indices to join the SP SmallCap 600 effective prior to the opening of trading on Thursday, May 27, 2021. 