Equistone Partners, a private equity firm, agreed to invest c.£110m (c.$145m) in adm Group, an independent global marketing services provider. “Equistone has demonstrated a deep understanding of our market through the process and we are delighted to welcome them to our business. Having a strong capital partner will enable us to increase the pace of investment in enhancing our services, technology platforms and fuel our continued growth," Justin Barton, adm Group CEO.