Margin Accounts Decoded: Initial, Maintenance, and Reg T on the Series 7

Margin questions are a guaranteed part of the Series 7. They require calculation, and they involve terminology that trips up candidates who have not worked through them deliberately. The underlying mechanics are not complicated once you understand what equity, debit balance, and long market value actually mean. This post walks through every margin concept you need, with worked examples for each calculation type.

The Basics: What a Margin Account Is

A margin account allows investors to borrow money from their broker-dealer to purchase securities. The broker-dealer extends credit and holds the purchased securities as collateral. The investor pays interest on the borrowed amount.

Three components define every margin account at any given moment:

• Long market value (LMV): The current market value of all securities held in the account
• Debit balance (DR): The amount owed to the broker-dealer (the loan)
• Equity: LMV minus DR

These three values are always related: Equity = LMV minus DR.

Regulation T: Initial Margin

Regulation T, set by the Federal Reserve, establishes the initial margin requirement for stock purchases. The current Reg T requirement is 50 percent.

When a customer buys stock on margin, they must deposit at least 50 percent of the purchase price. The broker-dealer can lend the other 50 percent.

Example: A customer buys $10,000 worth of stock. Under Reg T, they must deposit $5,000. The broker lends $5,000. The account now shows:

• LMV: $10,000
• DR: $5,000
• Equity: $5,000

The Reg T deposit requirement is based on the purchase price, not the market value after the fact. Once established, the Reg T calculation is done. What matters going forward is the maintenance requirement.

FINRA Maintenance Margin

After the initial purchase, FINRA requires that the customer maintain a minimum equity level in the account. The FINRA minimum maintenance requirement for long accounts is 25 percent of long market value.

If equity falls below 25 percent of LMV, the broker-dealer issues a margin call (sometimes called a maintenance call or house call). The customer must deposit additional cash or securities to restore the account to the required level.

Maintenance margin formula: Minimum equity = LMV times 0.25

Formula for the stock price that triggers a margin call:

The maintenance call price = DR divided by (1 minus 0.25), which simplifies to DR divided by 0.75.

Example: A customer has a DR of $6,000. At what stock price does a margin call occur?

$6,000 divided by 0.75 = $8,000 LMV

When LMV falls to $8,000, equity is $8,000 minus $6,000, which equals $2,000. That is exactly 25 percent of $8,000. Any further decline triggers a call.

Meeting a Margin Call

When a margin call occurs, the customer has options:

1. Deposit cash equal to the call amount
2. Deposit fully paid securities worth the call amount (the securities are then pledged as additional collateral)
3. Liquidate securities in the account (the proceeds reduce both LMV and DR)

Note: If the customer deposits cash, the full cash amount reduces the debit balance. If the customer liquidates securities, only a portion of the proceeds reduces the equity shortfall because selling reduces LMV as well as DR.

Excess Equity and Buying Power

When the market rises and account equity exceeds the Reg T requirement, the account has excess equity. Excess equity is also called SMA (Special Memorandum Account). SMA can be used to purchase additional securities without depositing new funds.

Excess equity formula: Actual equity minus required equity (50 percent of LMV)

Buying power: Excess equity divided by Reg T requirement (0.50), which means SMA multiplied by 2.

Example: An account has LMV of $15,000 and DR of $5,000. Equity is $10,000. Required equity under Reg T is $7,500 (50 percent of $15,000). Excess equity is $10,000 minus $7,500, which equals $2,500. Buying power is $2,500 divided by 0.50, which equals $5,000. The customer can buy an additional $5,000 of securities without depositing any new funds.

Short Margin Accounts

Short accounts work differently. When a customer sells short, they borrow shares from the broker-dealer, sell them, and receive the proceeds. They are hoping to buy the shares back later at a lower price.

In a short margin account:

• Short market value (SMV): The current market value of the borrowed (sold) shares
• Credit balance (CR): The proceeds from the short sale plus the initial margin deposit
• Equity: CR minus SMV

Reg T also applies to short sales: the initial margin requirement is 50 percent of the short sale proceeds.

Short account maintenance: FINRA requires 30 percent of SMV as minimum equity for short accounts (higher than the 25 percent required for long accounts).

Formula for short margin call price: CR divided by 1.30

Example: A customer sells short $8,000 worth of stock. They deposit $4,000 (50 percent of SMV). CR = $12,000 ($8,000 proceeds plus $4,000 deposit). At what price is there a margin call?

$12,000 divided by 1.30 = $9,231 SMV

If the stock rises to a total market value of $9,231, equity equals $12,000 minus $9,231, which is $769. That represents approximately 30 percent of $9,231. The short account is at the maintenance minimum.

Restricted Accounts

An account is restricted when its equity falls below the Reg T requirement (50 percent) but remains above the maintenance minimum (25 percent). In a restricted account, the customer cannot make additional purchases without depositing the required margin. However, they are not facing an immediate margin call.

If a customer in a restricted account wants to withdraw cash, they can only withdraw 50 percent of any proceeds from a sale (the retention requirement).

Common Series 7 Margin Mistakes

• Confusing Reg T with maintenance: Reg T applies at the time of purchase. Maintenance applies continuously. Different percentages, different purposes.
• Using 25 percent for short accounts: Short accounts have a 30 percent maintenance requirement, not 25 percent.
• Forgetting to use LMV (not DR) in the maintenance formula: The minimum equity is a percentage of market value, not of the loan.
• Mixing up SMA and buying power: SMA is excess equity. Buying power is SMA times 2 (because Reg T is 50 percent).

Work through at least 30 margin calculation problems before your exam. The arithmetic itself is not difficult, but the terminology requires precision. One misread term can send your entire calculation in the wrong direction.