Financial Industry Regulatory Authority (FINRA)
FINRA is a self-regulatory organization, meaning it’s not part of the government, but a non-profit organization which is designated by the government to be an examining authority.
A designated examning authority is expected to regulate its own members, and inspects their books and records.
FINRA’s members are Broker-Dealers (BDs), and is responsible for their licensing and regulation.
Note
FINRA does not regulate Registered Investment Advisers (RIAs) or Investment Adviser Representatives (IARs). That job falls to either the SEC, or the relevant State Securities Administrator.
The Securities Exchange Commission (SEC), a governmental body, oversees FINRA.