A rule of the Federal Reserve that excludes deficiencies of $500 or less in margin requirements as a necessary reason for the firm to liquidate the client's account to cover a margin call .
FIVE HUNDRED DOLLAR RULE
Meaning of FIVE HUNDRED DOLLAR RULE in English
Campbell R. Harvey. Hypertextual finance English glossary. Английский словарь гипертекстовых финансов. 2012