Margin Agreement: Hypothecation, Equity Rules, and Interest

A margin agreement is the contract you sign with a broker-dealer to open a margin account and borrow against your securities to buy more. It sets the interest you’ll pay on the loan, pledges everything in the account as collateral, lets the firm lend your shares to other customers, authorizes the firm to sell your holdings without warning if your equity drops too low, and routes any dispute into binding arbitration instead of court. Understanding each of those powers before signing matters because brokers exercise them routinely, and often at the worst moment.

What the Agreement Actually Contains

Most margin agreements bundle three components, sometimes into a single document and sometimes into separate ones.

The credit and hypothecation agreement establishes the loan itself. It defines how much you can borrow, what interest rate applies, and what secures the debt. Every security in the account, including shares you paid for entirely in cash, serves as collateral for the margin loan.¹

The loan consent agreement authorizes the firm to lend your securities to other investors, typically for short selling. This piece is technically optional. In practice, most brokers will decline to open the margin account without it.

The third piece is a set of required risk disclosures. The firm must provide them before or at the time the account is opened, and they warn you in plain terms about the possibility of losing more than you deposit, the firm’s right to sell your holdings without notice, and its ability to change margin requirements at any time.

Hypothecation: What Happens to Your Securities

Hypothecation is the mechanism that makes margin lending work. When you sign, you grant the firm a security interest in every asset held in the account. Your securities become collateral. The firm doesn’t own them, but it holds a legal claim it can enforce if you fail to repay the loan or meet a margin call.

The agreement also authorizes re-hypothecation, meaning the firm can pledge your securities to a bank as collateral for its own borrowing. This is how broker-dealers fund the margin loans they extend to customers. Federal law puts limits on the practice. Under SEC Rule 8c-1, a firm cannot pledge customer securities under liens that exceed the aggregate indebtedness of all its customers whose securities are being pledged, and it cannot commingle your securities with the firm’s own inventory under any pledge without your written consent.²

You keep the economic ownership of your shares. Dividends, voting rights, and gains still belong to you. The broker controls custody and can use the shares as collateral. That split between ownership and control is one of the less obvious tradeoffs of margin trading.

Consenting to Have Your Shares Lent Out

A separate clause authorizes the broker to lend your securities to customers or market participants who want to sell them short. When someone short-sells a stock, they need actual shares to deliver to the buyer, and your margin account is one of the places those borrowed shares come from.

You can refuse to sign the loan consent, and the firm cannot legally condition margin credit on your consent. Most firms will nonetheless decline to open the account without it. If your shares are on loan, you may lose voting rights during the lending period, and you may receive payments in lieu of dividends rather than qualified dividends, which changes the tax treatment.

The Equity You Have to Keep in the Account

Three layers of margin rules govern how much of your own money has to stay in the account: a federal floor, a regulatory minimum, and the broker’s own threshold.

Initial Margin

The Federal Reserve Board’s Regulation T sets the initial margin requirement at 50% of the purchase price for most equity securities. Buying $20,000 of stock on margin requires at least $10,000 of your own money. Some firms require more than 50% for volatile or thinly traded securities.³

Maintenance Margin

After the purchase, your account has to maintain a minimum equity percentage against the current market value of your holdings. FINRA Rule 4210 sets the regulatory floor at 25% for long positions. That’s genuinely just a floor. Most brokerages impose house requirements of 30% to 40%, and the rule itself encourages firms to formulate their own standards and review the need for higher requirements on individual securities or accounts.⁴

Concentrated positions get hit especially hard. Under FINRA Rule 4210, control and restricted securities that represent more than 10% of a company’s outstanding shares face maintenance requirements that scale upward in tiers, reaching 100% of market value once concentration hits 30% or more of outstanding shares.⁴

What Can and Cannot Be Margined

Regulation T defines which securities qualify as margin securities. Anything outside that definition requires 100% cash. Eligible categories include securities listed on a national exchange, Nasdaq-listed securities, mutual funds and unit investment trusts registered under the Investment Company Act, non-equity securities like bonds, and certain foreign stocks that meet specific criteria.³ Over-the-counter stocks not listed on Nasdaq or a national exchange, penny stocks, and newly issued securities that haven’t traded publicly long enough are typically excluded. OTC stocks not already on the marginable list must have been publicly traded for at least six months before they become eligible, and firms may designate specific securities as non-marginable based on their own risk assessment.⁴

How the Interest Gets Calculated

Margin interest accrues on the outstanding loan balance, called the debit balance. Brokers typically start with a benchmark known as the broker call rate, the rate banks charge brokers for margin lending, and add a spread that varies by firm and account size. The rate is variable and fluctuates with market conditions. Interest compounds and is charged to your account regardless of whether your investments gain or lose value. A losing position can cost you the loss itself plus the interest that accumulated while you held it.

Margin Calls and the Broker’s Right to Sell

This is the part of the agreement with the sharpest teeth. A margin call happens when your account equity drops below the maintenance margin requirement, whether that’s the FINRA 25% minimum or your broker’s higher house requirement. If your positions lose enough value, the loan becomes under-collateralized and the firm demands more equity.⁵

What catches most investors off guard is the response. The margin agreement gives the broker the right to sell any securities in your account to bring equity back above the required level. The firm doesn’t need your approval. It doesn’t have to call you first. It picks which securities to sell and at what price, with sole discretion. If the liquidation happens during a sharp downturn and the sale proceeds don’t cover the full debit balance, you’re personally liable for the remaining deficit.¹

Firms can also raise house maintenance requirements at any time. Regulation T explicitly permits exchanges, FINRA, and individual broker-dealers to impose additional requirements beyond the regulatory minimums for their own protection.³ During volatility, a firm might increase its house requirement from 30% to 50% overnight. That single change can trigger a margin call in an account that was fully compliant the day before, even if your holdings haven’t lost a cent.

Arbitration Instead of Court

Nearly every margin agreement includes a predispute arbitration clause, governed by FINRA Rule 2268. By signing, you waive the right to sue the firm in court and agree to resolve any disputes through binding arbitration, typically administered by FINRA’s own dispute resolution forum. You also give up the right to a jury trial and, in most cases, the right to participate in a class action related to your account.⁶

Arbitrator decisions are final and binding, with extremely limited grounds for appeal. The process is generally faster than litigation. If you ever believe your broker mishandled a margin call or liquidated your account improperly, arbitration is almost certainly the only path to recover losses.

The Risk Disclosures You Should Read First

FINRA Rule 2264 requires your broker to provide a written margin disclosure statement before or at the time you open the account. The disclosures translate the legal language elsewhere in the agreement into plain terms:

You can lose more than you deposit. A margin account can generate losses that exceed your initial investment, and you’re personally responsible for the shortfall.
The firm can sell your securities without contacting you. The broker is not required to issue a margin call before liquidating, though many firms attempt to as a courtesy.
The firm can increase margin requirements at any time. House requirements are not fixed, and there’s no advance notice requirement or grandfathering for existing positions.
You are not entitled to choose which securities are sold. If the firm liquidates to meet a call, it decides what goes and at what price.
You are not entitled to a time extension. Even if the firm offers one, it can still act immediately without waiting for you to deposit additional funds.

These aren’t hypothetical worst cases. Brokers exercise these rights routinely during market downturns.⁷

What SIPC Does and Doesn’t Cover

The Securities Investor Protection Corporation protects customers if their brokerage firm fails, and margin accounts get treated specifically. SIPC coverage tops out at $500,000 per customer, including a $250,000 sublimit for cash. It covers the custody function, working to restore securities and cash that were in your account when the firm’s liquidation begins.⁸

For margin accounts, SIPC calculates net equity, subtracting the outstanding margin loan balance from the total value of your account. An account holding $400,000 in securities with a $150,000 margin debit balance has $250,000 in net equity for SIPC purposes. SIPC does not protect against market losses, bad investment decisions, or the decline in value of securities you bought on margin. It also does not cover commodity futures contracts unless they’re held in a special portfolio margining account.⁸

1
SEC.gov. Investor Bulletin: Understanding Margin Accounts
2
GovInfo. 17 CFR 240.8c-1 – Hypothecation of Customers’ Securities
3
eCFR. Part 220 – Credit by Brokers and Dealers (Regulation T)
4
FINRA. FINRA Rule 4210 – Margin Requirements
5
FINRA. Know What Triggers a Margin Call
6
FINRA. FINRA Rule 2268 – Requirements When Using Predispute Arbitration Agreements for Customer Accounts
7
FINRA. Margin Regulation
8
SIPC. What SIPC Protects