Margin Call

A margin call is a brokerage firm's demand that an investor deposit additional cash or securities into a margin account after the account's equity has fallen below the required minimum. The Securities and Exchange Commission's investor education describes the firm's authority when a shortfall occurs in specific, unqualified terms: the firm "can require you to deposit cash or securities to your account immediately, or sell any of the securities in your account to cover any shortfall, without informing you in advance." A margin call is therefore not only, or even primarily, a request; it is one form the firm's response can take, and the firm's power to simply liquidate the account is available at the same moment.

This page is about the demand and its consequences specifically. How a margin account and its borrowing work in the first place, including the ongoing interest cost and the initial requirement to open one, are covered on our page for margin; leverage as a general concept in investing is covered on our own page for that subject.

The two qualifications the SEC attaches to a margin call are what most investors get wrong about it, and both remove an assumption people routinely make. The first is that "the brokerage firm decides which of your securities to sell," not the investor, so a shortfall in one holding can be covered by selling a different, unrelated one the investor would have preferred to keep. The second is timing: "even if the brokerage firm notifies you that you have a certain number of days to cover the shortfall, it still may sell your securities before then." A stated deadline in a margin call notice is not a commitment the firm is bound by; it is, at most, a courtesy the firm may choose not to honor. Together, those two facts mean the investor controls neither which holdings are sold nor when, once a shortfall exists.

Two different federal floors govern margin, at two different moments, and confusing them produces the wrong number for the situation an investor is actually in. Regulation T, the Federal Reserve's rule, sets the initial margin requirement, the amount of equity required the moment a margin equity security is first bought on margin, at "50 percent of the current market value of the security or the percentage set by the regulatory authority where the trade occurs, whichever is greater," under 12 CFR 220.12(a). That 50% governs the purchase itself. A separate figure governs the position afterward, for as long as it is held: FINRA Rule 4210(c)(1) sets maintenance margin at "25 percent of the current market value of all margin securities... 'long' in the account." A margin call is triggered by a breach of this ongoing maintenance requirement, not by the 50% initial figure, which applies only at the moment of purchase.

Both of those figures are floors, and the number that actually governs a given account is usually higher. FINRA's rule sets a regulatory minimum; it does not stop a firm from requiring more. The SEC has noted that broker-dealers "may always collect additional margin from customers than required" under the rule, and its own investor education adds that a firm "may at any time change the threshold at which customers are subject to a margin call." So a 25% maintenance figure describes the regulatory floor, not necessarily the trigger point on any particular account, and the practical instruction is to read the margin agreement and ask the firm for its current house requirement, because that number, not the regulatory minimum, is the one that will actually be enforced.

The sequence a margin call sets off has no guaranteed pause built into it, which is the point most likely to surprise a first-time borrower. Once equity falls below the applicable requirement, whether that requirement is the regulatory floor or a higher house figure, the firm may act immediately: demand a deposit, sell securities, or both. There is no federally mandated waiting period the investor is entitled to before a sale can happen, and a notice giving a specific number of days to cure the shortfall is, per the SEC's own description, not a binding limit on when the firm may act.

The forced sale tends to arrive at the worst possible moment for the investor, which is a structural feature of the mechanism rather than a coincidence. A margin call happens because the position has already fallen in value; selling to meet it realizes that loss and removes the chance to hold through a later recovery, exactly when an unleveraged holder facing the same price decline would be free to simply wait. This is the specific mechanism behind the asymmetry our page on margin describes in general terms: a margin loan magnifies losses more than it magnifies gains, because the loan is a fixed claim that survives a price decline intact, and it is a margin call that turns that arithmetic fact into an actual, involuntary sale.

A brokerage firm monitors the equity in every margin account against the applicable maintenance requirement, whichever of the regulatory floor and the firm's own house requirement is higher. When equity falls below that requirement, the firm can issue a margin call demanding a deposit, or move directly to selling securities in the account, at its own discretion about which holdings and when.

A hypothetical illustration using the 25% maintenance floor. Suppose an investor's margin account holds securities worth $20,000, financed with a $12,000 loan, so equity is $8,000 (40% of $20,000). If the securities fall in value to $14,000, the loan is unchanged at $12,000, so equity is now $2,000 (14.3% of $14,000, calculated as $2,000 ÷ $14,000), below the 25% maintenance floor. To restore equity to 25% of the current $14,000 value, the account needs $3,500 of equity (25% × $14,000), a shortfall of $1,500 ($3,500 − $2,000) that must be covered by a deposit, by selling securities, or by some combination the firm chooses. If the investor's own firm imposes a higher house requirement of, say, 35% instead of the 25% regulatory floor, the required equity at $14,000 of holdings would instead be $4,900 (35% × $14,000), a larger shortfall of $2,900, which is why the firm's own agreement, not the regulatory minimum, is the number that actually matters. All figures are illustrative.

Pros

• The trigger is at least published: the applicable maintenance requirement, whether the FINRA floor or the firm's higher house figure, is stated in the margin agreement rather than left undisclosed.
• A margin call, when it is simply a request for a deposit rather than an immediate sale, gives the investor a chance to add funds and keep a position they still believe in.
• Understanding the mechanism in advance lets an investor manage a margin account's equity cushion deliberately, rather than being surprised by a call at the worst moment.

Cons

• The firm decides which securities to sell to cover a shortfall, which can force the sale of a holding the investor would have preferred to keep.
• A stated cure period is not binding on the firm, which may sell before any deadline it has given.
• The event is triggered by a price decline that has already happened, so the resulting sale realizes a loss and removes the chance to hold through a recovery.
• The number that actually governs an account is often a house requirement higher than the regulatory floor, and it can change at any time at the firm's discretion.