what are magin accounts
margin account. A brokerage account that permits an investor to purchase securities on credit and to borrow on securities already in the account. Buying securities on credit and borrowing on securities are subject to standards established by the Federal Reserve and/or by the firm carrying the account.argin account. A brokerage account that permits an investor to purchase securities on credit and to borrow on securities already in the account. Buying securities on credit and borrowing on securities are subject to standards established by the Federal Reserve and/or by the firm carrying the account.