How to Become a Trading Institution
The process of becoming a Trading Institution on the NASD OTC Securities Exchange is easy and straightforward.
Trading Institutions are required to forward duly completed Form 1a – Registering a Trading Institution and 1b - Registration as an Authorized Trader and the necessary fees needed for the registration from the list NASD Registration Fees.

There are three categories of Trading Institutions on the platform
CategoryTrade on behalf of ClientsTrade on behalf of itself

Other relevant documentation includes:
Trading Rules:
Securities Admission:

Other relevant documents can be found here