What Is a Special Memorandum Account (SMA) in Margin Trading?
Behind every margin account sits a second, quieter figure that most account holders rarely think about until it becomes useful: the special memorandum account, or SMA. It’s less a place money sits and more a running tally.
The short answer
A special memorandum account is a ledger within a margin account that tracks excess equity beyond what’s required to meet the initial margin requirement. That excess can typically be withdrawn as cash or used as additional buying power for new purchases. Unlike a checking or savings balance, an SMA is a calculated line item, not a separate pool of actual funds, and it generally only increases — it doesn’t shrink automatically just because the account’s market value falls.
How the balance builds up
An SMA typically grows when a position gains value, when cash or securities are deposited beyond what’s needed to satisfy the initial requirement, or when dividends are received. As a position appreciates, the excess equity created by that gain gets credited to the SMA, effectively banking some of the account’s improved position. Because the SMA is a running credit rather than a snapshot of current equity, it generally doesn’t decrease just because the market value of holdings later declines — though how it can be used is still constrained by the account’s actual current equity.
Why it’s tracked separately from buying power
It’s tempting to think of the SMA balance and total buying power as the same thing, but they serve different functions. Buying power reflects what can currently be used to purchase securities right now, factoring in the account’s live equity and the debit balance already outstanding. The SMA is more like a floor of credited excess equity that has accumulated over time, which contributes to buying power calculations without being identical to them.
What it can actually be used for
- Withdrawing cash. Some or all of an SMA balance can typically be taken out of the account, subject to having sufficient actual equity to support the withdrawal.
- Making new purchases. SMA can effectively function as leverage-backed buying power for additional securities, without depositing new cash.
- Providing a cushion. A larger SMA balance can indicate more room before an account approaches a maintenance requirement problem, since it reflects a history of excess equity.
Why it doesn’t erase market risk
Having a healthy SMA balance doesn’t mean an account is immune to a margin call deficiency — SMA reflects a specific bookkeeping calculation, not a guarantee of available cash in every scenario. A sharp decline in the value of held securities can still push actual equity below a maintenance requirement even while the SMA figure on paper looks favorable, because the two are governed by different rules within the margin account agreement.
A practical habit
Reviewing both the SMA balance and the account’s current equity, rather than relying on SMA alone, gives a fuller picture of how much flexibility actually exists. Since SMA is a specialized figure with its own rules for building up and drawing down, it’s worth understanding as a distinct concept from the account’s everyday market value.