This page describes the margin requirements of the Board of Governors of the Federal Reserve System under Regulation T (applicable to broker-dealers), Regulation U (applicable to other lenders on securities collateral) and Regulation X (applicable to borrowers). It also covers the additional requirements that apply to broker-dealers to collect margin with respect to securities under the rules of the SEC and the rules of the securities self-regulatory organizations, particularly FINRA Rule 4210. See also the separate pages that deal with (i) TBA transactions and the MSFTA Agreement and (ii) Security Futures, including margin on security futures.