Abry Partners, a leading Boston-based private equity firm, made a significant investment in Millennium Trust Company, a leading provider of technology-enabled retirement services and institutional custody solutions for businesses, institutions, advisors, and individuals. Parthenon Capital Partners will retain a minority stake in Millennium Trust. Financial terms were not disclosed. “Millennium Trust’s expertise and continuous innovation have created a leader in custody solutions, and we believe the Company will continue to grow and evolve in the markets it serves.” Azra Kanji, Abry Partner.