The basic margin requirement is certain percentage of the current value of the security futures contract, although some strategies may have lower margin requirements. Requests for additional margin are known as “margin calls.” Both buyer and seller must individually deposit the required margin to their respective accounts.

It is important to understand that individual brokerage firms can, and in many cases do, require margin that is higher than the exchange requirements. Additionally, margin requirements may vary from brokerage firm to brokerage firm. Furthermore, a brokerage firm can increase its “house” margin requirements at any time without providing advance notice, and such increases could result in a margin call.

For example, some firms may require margin to be deposited the business day following the day of a deficiency, or some firms may even require deposit on the same day. Some firms may require margin to be on deposit in the account before they will accept an order for a security futures contract. Additionally, brokerage firms may have special requirements as to how margin calls are to be met, such as requiring a wire transfer from a bank, or deposit of a certified or cashier’s check. You should thoroughly read and understand the customer agreement with your brokerage firm before entering into any transactions in futures contracts.

If through the daily cash settlement process, losses in the account of a security futures contract participant reduce the funds on deposit (or equity) below the maintenance margin level (or the firm’s higher “house” requirement), the brokerage firm will require that additional funds be deposited.

If additional margin is not deposited in accordance with the firm’s policies, the firm can liquidate your position in futures contracts or sell assets in any of your accounts at the firm to cover the margin deficiency. You remain responsible for any shortfall in the account after such liquidations or sales. Unless provided otherwise in your customer agreement or by applicable law, you are not entitled to choose which futures contracts, other securities or other assets are liquidated or sold to meet a margin call or to obtain an extension of time to meet a margin call.

Brokerage firms generally reserve the right to liquidate a customer’s futures contract positions or sell customer assets to meet a margin call at any time without contacting the customer. Brokerage firms may also enter into equivalent but opposite positions for your account in order to manage the risk created by a margin call.

Some customers mistakenly believe that a firm is required to contact them for a margin call to be valid, and that the firm is not allowed to liquidate securities or other assets in their accounts to meet a margin call unless the firm has contacted them first. This is not the case. While most firms notify their customers of margin calls and allow some time for deposit of additional margin, they are not required to do so. Even if a firm has notified a customer of a margin call and set a specific due date for a margin deposit, the firm can still take action as necessary to protect its financial interests, including the immediate liquidation of positions without advance notification to the customer.

Here is an example of the margin requirements for a long security futures position.

A customer buys 3 July EJG security futures at 71.50. Assuming each contract represents 100 shares, the nominal value of the position is $21,450 (71.50 x 3 contracts x 100 shares). If the initial margin rate is 20% of the nominal value, then the customer’s initial margin requirement would be $4,290. The customer deposits the initial margin, bringing the equity in the account to $4,290.

First, assume that the next day the settlement price of EJG security futures falls to 69.25. The marked-to-market loss in the customer’s equity is $675 (71.50 – 69.25 x 3 contacts x 100 shares). The customer’s equity decreases to $3,615 ($4,290 – $675).

The new nominal value of the contract is $20,775 (69.25 x 3 contracts x 100 shares). If the maintenance margin rate is 20% of the nominal value, then the customer’s maintenance margin requirement would be $4,155. Because the customer’s equity had decreased to $3,615 (see above), the customer would be required to have an additional $540 in margin ($4,155 – $3,615).

Alternatively, assume that the next day the settlement price of EJG security futures rises to 75.00. The mark-to-market gain in the customer’s equity is $1,050 (75.00 – 71.50 x 3 contacts x 100 shares). The customer’s equity increases to $5,340 ($4,290 + $1,050). The new nominal value of the contract is $22,500 (75.00 x 3 contracts x 100 shares). If the maintenance margin rate is 20% of the nominal value, then the customer’s maintenance margin requirement would be $4,500. Because the customer’s equity had increased to $5,340 (see above), the customer’s excess equity would be $840.

The process is exactly the same for a short position, except that margin calls are generated as the settlement price rises rather than as it falls. This is because the customer's equity decreases as the settlement price rises and increases as the settlement price falls.

Because the margin deposit required to open a security futures position is a fraction of the nominal value of the contracts being purchased or sold, security futures contracts are said to be highly leveraged. The smaller the margin requirement in relation to the underlying value of the security futures contract, the greater the leverage.

Leverage allows exposure to a given quantity of an underlying asset for a fraction of the investment needed to purchase that quantity outright. In sum, buying (or selling) a security futures contract provides the same dollar and cents profit and loss outcomes as owning (or shorting) the underlying security. However, as a percentage of the margin deposit, the potential immediate exposure to profit or loss is much higher with a security futures contract than with the underlying security.

For example, if a security futures contract is established at a price of $50, the contract has a nominal value of $5,000 (assuming the contract is for 100 shares of stock). The margin requirement may be as low as 20%. In the example just used, assume the contract price rises from $50 to $52 (a $200 increase in the nominal value). This represents a $200 profit to the buyer of the security futures contract, and a 20% return on the $1,000 deposited as margin. The reverse would be true if the contract price decreased from $50 to $48. This represents a $200 loss to the buyer, or 20% of the $1,000 deposited as margin. Thus, leverage can either benefit or harm an investor.

Note that a 4% decrease in the value of the contract resulted in a loss of 20% of the margin deposited. A 20% decrease would wipe out 100% of the margin deposited on the security futures contract.