Margin Agreement, Initial and Maintenance Margin, Margin Calls, and Restricted Accounts

The most general definition of margin, one that covers both buying and shorting securities, is the ratio of the equity of the account divided by the value of the securities. The equity of the account is simply what is left when the debit balance is paid in full or the shorted stocks have been bought back and returned to the lender.

If money is borrowed, then it must be paid back, so the amount borrowed plus the accrued margin interest is a debit to the account; if stocks are sold short, then the shorted stocks must be bought back, so the value of the shorted stocks are a debit to the account.

Margin  =

Equity ───────────── Value of Securities

To use margin for trading, you have to open a margin account by signing a margin agreement. The agreement stipulates, among other things, the initial margin requirement as a percentage, and the margin maintenance percentage. Any securities bought in a margin account are held in the broker’s street name, and the margin agreement usually gives the broker the right to lend the securities out for a short sale.

Margin trading is governed by the Federal Reserve, and other self-regulatory organizations (SROs), such as the New York Stock Exchange and the NASD. Regulation T, promulgated by the Federal Reserve, requires that the minimum deposit be $2,000, and that the initial margin percentage be at least 50%.

There is also a minimum maintenance margin requirement of 25%. The exchanges or the brokerages can set stricter requirements than those required by the Federal Reserve if they choose. At most brokerages, the maintenance margin requirement is set higher, usually at 30%.

The margin ratio cannot be less than the maintenance margin rate. If the margin ratio falls below 50%, but remains above the maintenance margin requirement, then the account will be restricted. No additional securities can be bought or sold short in a restricted account, unless the trader deposits additional cash or securities to increase the margin level to at least 50%.

The amount of margin available will depend on the price of the securities. If margin is used to buy securities, then the amount of margin increases with the market value of the securities, but if the margin is used to short securities, then the amount of margin is inversely related to the price of the shorted securities, and vice versa.

If the equity does drop below the maintenance margin requirement, then the broker will issue a margin call, requesting that additional cash or securities be deposited so that the margin ratio of the account is equal to at least 50%. If you do not respond to the margin call, then your broker will sell enough of your securities that were purchased on margin and/or buy back your shorted securities at the market to bring your margin ratio back to the initial margin requirement of 50%.