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. (We will also be providing separate pages dealing with both (x) related regulatory issues such as SEA Section 11(d) and swaps margin rules and (y) relevant contract types, such as securities lending agreements and repurchase agreements. These pages will be available shortly.)