Is the Securities and Exchange Commission is responsible for setting margin requirements?

Yes, the Securities and Exchange Commission (SEC) is involved in setting margin requirements, but it works in conjunction with the Financial Industry Regulatory Authority (FINRA) and the Federal Reserve. The SEC establishes regulations that govern the securities industry, while the Federal Reserve has the authority to set margin requirements for credit extended by brokers and dealers. FINRA also enforces rules related to margin trading among its member firms. Thus, margin requirements are determined through collaboration among these regulatory bodies.