Member institutions are divided into ordinary members that are securities regulators, associate members that are other authorities, and affiliate members such as self-regulatory organizations. In Japan, the Financial Services Agency is an ordinary member. As of June 2023, there were 239 member institutions.
The international principles and standards set by IOSCO do not, in general, legally bind its members. Members are encouraged to act in line with them and to work toward compliance with the principles. In derivatives, IOSCO developed the international standard for margin requirements on uncleared trades jointly with the Basel Committee on Banking Supervision (BCBS).