CHARLOTTE, N.C.--(BUSINESS WIRE)--Frontier Capital ("Frontier") is pleased to announce the sale of Frontier portfolio company, Celergo LLC ("Celergo"), a leading provider of global payroll management services, to ADP® (NASDAQ: ADP). Frontier, based in Charlotte, NC, is a leading middle-market growth equity firm focused exclusively on software and tech-enabled business services companies. Founded in 2003, Celergo offers multi-country payroll in 150 countries and combines a proprietary cloud-base