Margin Call Explained: What Every Investor Should Know

A margin call is a demand from your broker to add cash or securities to your account because your equity has fallen below the required minimum for positions bought with borrowed money. If you do not meet the call in time, the broker can sell your holdings, often without asking which ones. This page is for investors who use, or are considering, a margin account and want the mechanics of a margin call explained in plain language: what triggers one, what happens next, how to respond, and how to keep it from happening. If you take one step after reading, review your account's maintenance requirement and current equity cushion today.

What is a margin call?

Buying on margin means borrowing part of the purchase price of securities from your broker, using the account's holdings as collateral. The loan magnifies both gains and losses: a 10% move in the stock is a larger percentage move on the cash you actually put in.

Because the broker's loan is secured by your securities, the broker requires your equity, the account's value minus what you owe, to stay above a minimum percentage. When falling prices push equity below that line, the broker issues a margin call: a demand to restore the cushion by depositing funds, adding securities, or selling positions.

A margin call is not a courtesy notice. It is a contractual demand under your margin agreement, and brokers can act on it quickly.

How margin accounts and margin requirements work

Margin lending in the United States operates under federal rules and self-regulatory requirements, with brokers layering their own, often stricter, "house" requirements on top. Three numbers matter:

• Initial margin. Under Federal Reserve Regulation T, the initial requirement is generally 50% for eligible margin-equity securities, subject to exceptions and broker rules.
• Maintenance margin. FINRA's minimum for long margin securities is generally 25% of current market value, while brokers commonly impose higher house requirements.
• House requirements. Brokers can raise requirements on specific securities at any time, sometimes overnight, which by itself can trigger a call even when prices have not moved.

FINRA's current margin-call guidance explains the 50% initial framework, 25% maintenance minimum, higher house requirements, and the broker's ability to liquidate securities without consulting the customer.

A worked example

Say you buy $20,000 of stock using $10,000 of your own cash and a $10,000 margin loan, and your broker's maintenance requirement is 30%.

At a 30% requirement, your account value can fall to about $14,285 before equity breaches the line. The call amount is the sum needed to restore the required percentage, roughly $200 of new equity in the last row, and more if the stock keeps sliding while you decide.

What triggers a margin call

• Falling prices. The most common cause: the market value of margined positions drops far enough that equity breaches the maintenance requirement.
• Raised requirements. Brokers increase house margin on volatile names, hard-to-borrow stocks, or concentrated accounts. A requirement hike can create a call with no price change at all.
• Concentration. A single position dominating the account often carries a higher requirement, and its fall hits equity harder than a diversified book would.
• Volatility events. Sharp market-wide drawdowns produce calls across many accounts simultaneously, which is also when selling to meet them is most painful.
• Withdrawals and fees. Taking cash out of a thinly cushioned account, or accumulating margin interest on the loan, can quietly erode equity toward the line.

What happens if you do not meet a margin call

The consequences escalate quickly:

1. Forced liquidation. The broker can sell securities in your account to restore the requirement. Your margin agreement typically allows this without advance notice and without letting you choose which positions go.
2. Locked-in losses. Forced sales happen at prevailing prices, often near the bottom of a decline, converting paper losses into real ones.
3. Tax consequences. Involuntary sales can realize gains or losses at unplanned times, complicating your tax position.
4. A remaining debt. If liquidation proceeds do not cover the loan, you still owe the difference. A margined account can lose more than the cash you deposited.
5. Account restrictions. Repeated calls can lead to reduced borrowing limits, higher requirements, or closure of margin privileges.

Brokers are not obligated to give you the courtesy period you might expect. In fast markets, sales can begin the same day the call is issued.

How to respond to a margin call

If you receive a call, act deliberately and fast:

1. Verify the numbers. Check the call amount, the deadline, and which positions drove the breach.
2. Choose your cure. You can deposit cash, transfer in marginable securities, or sell positions yourself. Selling your own choice of holdings is usually better than letting the broker choose.
3. Prioritize speed. Transfers that settle in days may not arrive before the deadline. Confirm timing with the broker before relying on them.
4. Do not average down to fix it. Buying more of the falling stock with more borrowed money increases the exact exposure that caused the call.
5. Talk to the broker. Extensions exist in some cases, but treat them as exceptions, not entitlements, and get any agreement in writing.