margin call

A call from a broker to a customer (called a maintenance margin call) or from a clearinghouse to a clearing member (called a variation margin call) demanding the deposit of cash or marginable securities to satisfy the Regulation T requirements and the house maintenance requirement for the purchase or short sale of securities or to cover an adverse price movement. also called federal margin call or Reg. T Call (for NASD requirements) or house call (for brokerage requirements).