A margin account is a brokerage account in which eligible assets secure credit extended by the broker.
A margin account is a brokerage account in which eligible cash and securities secure credit extended by the broker. The investor can use the credit to buy securities or for other permitted purposes, while the broker retains contractual rights over collateral if equity becomes insufficient.
A margin account creates leverage. The market value of the investments can change while the loan remains payable and interest continues to accrue. If collateral falls or requirements rise, the broker may restrict the account, demand additional equity, or sell securities under the margin agreement.
| Feature | Cash account | Margin account |
|---|---|---|
| Purchase funding | Settled cash or fully paid securities | Investor equity plus permitted broker credit |
| Collateral | No securities-purchase loan to secure | Account assets generally secure the debit balance |
| Interest | No margin interest on a broker debit | Interest accrues under the broker’s rate schedule |
| Loss relative to deposit | Generally limited to the amount invested in a fully paid long position | Can exceed the investor’s initial cash contribution |
| Liquidation rights | Account can still face settlement or other restrictions | Broker may liquidate collateral to protect its loan and margin position |
| Short selling and advanced strategies | Usually unavailable | Commonly requires margin approval plus product permissions |
A margin account is not the same as approval for every leveraged strategy. Options, short selling, portfolio margin, futures, and other products can require separate agreements, suitability or eligibility checks, and risk limits.
The investor deposits cash or eligible securities. The broker applies collateral values and margin requirements, then calculates the account’s equity, debit, excess equity, and buying power. When credit is used, the broker records a debit balance and charges interest under the account agreement.
| Account item | Meaning |
|---|---|
| Market value | Current value of securities and other marked positions |
| Margin debit | Amount owed to the broker before any unposted interest or adjustments |
| Account equity | Assets less the debit and other account liabilities |
| Required margin | Equity or collateral required under applicable rules and house policy |
| Excess equity | Equity above the applicable requirement |
| Buying power | Broker-calculated capacity for new transactions, often after multipliers and reservations |
| Margin loan availability | Amount the broker currently indicates may be borrowed or withdrawn under its methodology |
These figures are related but not interchangeable. A screen can show positive buying power while a withdrawal, concentrated purchase, non-marginable security, open order, or price change produces a different result.
Buying on margin means purchasing securities with a combination of investor equity and broker credit. The securities become part of the collateral pool, but their value can decline without reducing the amount borrowed.
Assume an investor deposits $15,000 and buys $25,000 of eligible stock, creating a $10,000 margin debit.
| Scenario | Stock value | Debit before interest | Investor equity | Return on initial $15,000 equity |
|---|---|---|---|---|
| At purchase | $25,000 | $10,000 | $15,000 | 0% |
| Stock rises 20% | $30,000 | $10,000 | $20,000 | 33.3% |
| Stock falls 20% | $20,000 | $10,000 | $10,000 | (33.3%) |
The example excludes interest, commissions, taxes, dividends, and changing margin requirements. It shows why a 20% price move creates a larger percentage change in investor equity. A sufficiently large decline can reduce equity below zero, leaving an amount still owed after liquidation.
A margin loan is broker credit secured by assets in the margin account. Margin debt is the outstanding amount borrowed at a point in time. The terms are often used together, but one describes the credit arrangement and the other the current balance.
The investor generally remains responsible for the debit regardless of why the collateral declined. The broker may permit loan proceeds to fund securities purchases or certain non-securities uses, but using proceeds elsewhere does not remove collateral, interest, call, or liquidation risk from the brokerage account.
At the market level, aggregate customer margin debt can be used as a broad indicator of securities borrowing. It does not by itself show whether investors are bullish, which positions carry the leverage, the quality of collateral, or when borrowing will reverse. Account-level credit decisions should not be inferred from aggregate statistics.
Excess equity is account equity above an applicable margin requirement. Buying power converts available resources into estimated transaction capacity under the broker’s rules. The figures can differ because a broker may apply product-specific percentages, concentration charges, portfolio offsets, open-order reservations, and withdrawal limits.
Buying power can fall when:
Buying power is not cash, a guaranteed credit line, or a measure of how much loss the account can safely withstand.
Margin loan availability is the amount a broker currently calculates as available for borrowing or withdrawal against eligible assets. It is a narrower operational figure than total market value and can be lower than displayed trading buying power.
Availability should be checked against the proposed use. A withdrawal reduces account assets, while a purchase adds a position that may itself have a margin value. Broker methodology, settlement status, concentration, security price, and account restrictions can make the two transactions affect capacity differently.
A displayed amount is not necessarily committed until a transaction is accepted and settled. The broker can change collateral values or house requirements under the agreement and applicable rules.
Margin interest is the financing cost charged on a margin debit. Brokers may use tiered rates, a base rate plus a spread, daily balance methods, different day-count conventions, and periodic posting. The account agreement and rate schedule control the charge.
A simple estimate is:
1estimated interest = average debit x annual rate x days / day-count basis
If the average debit is $10,000, the annual rate is 9%, and the debit remains for 120 days using a 360-day estimate, interest is $10,000 x 9% x 120 / 360 = $300.
The $300 raises the investment’s break-even amount. If interest is added to the debit instead of paid in cash, it also reduces account equity and margin cushion. Actual charges can differ because balances and rates change daily, posting dates vary, and other fees may apply.
A non-marginable security cannot be purchased using ordinary margin credit or does not receive the same collateral value as eligible margin securities. Eligibility depends on applicable rules and broker policy, not merely on whether the security trades in a brokerage account.
Securities can be non-marginable or subject to high house requirements because of product type, offering status, price, liquidity, volatility, concentration, trading restrictions, or broker risk policy. A security can also become less marginable after purchase, reducing buying power or creating a deficiency.
| Status | Purchase funding | Collateral effect |
|---|---|---|
| Fully paid cash holding | Investor pays full purchase price | May or may not receive collateral value later |
| Marginable security | Can qualify for permitted margin credit | Receives value subject to applicable requirement |
| Non-marginable security | Generally must be fully funded for the purchase | Provides no or limited margin capacity under the broker’s treatment |
| Concentrated or specially margined security | May remain technically marginable | Receives reduced value or a higher requirement |
The agreement and related disclosures should be reviewed for:
The operational record also matters: daily account statements, trade confirmations, rate schedules, margin notices, security-eligibility screens, and liquidation records should reconcile to the account calculation.
This page is educational and does not recommend opening or using a margin account. Margin suitability, account rights, tax consequences, and regulatory treatment depend on the investor, broker, product, agreement, and jurisdiction.
The SEC’s Investor Bulletin: Understanding Margin Accounts explains cash and margin accounts, loans, interest, liquidation rights, transfers, securities lending, and the risk of losses exceeding the initial investment.
FINRA’s margin regulation page provides access to Rule 4210 and margin-related interpretations and reporting information. The Federal Reserve publishes Regulation T, which governs covered broker-dealer credit arrangements.