International Shareholder Services (ISS) is an advisory firm that assists clients with research in asset management, proxy voting, and corporate governance. It has gained a reputation in the business sector for supporting the appointment of board members with activist agendas.
The smallest but most notable branch of ISS is the Special Situations Research Group, which conducts research and influences the outcomes of contested corporate boardroom seats.  This smaller branch typically recommends activists of various types to the aforementioned board seats. ISS is so well-known that firms such as CamberView and Strategic Governance Advisors were created to prepare corporate clients for having to battle against ISS for contested board seats. 
ISS is a private company, and as such receives revenue from its clients, with the largest being the investment management companies BlackRock and Vanguard Group, and financial services company State Street Corp. 
Gary Retelny is the president and CEO of ISS, and previously worked at ISS’s former parent company MSCI Inc. as the head of strategy and business development.