A margin call happens when your account equity falls below your broker's maintenance margin requirement — under FINRA Rule 4210 that is typically 25% of the position's market value, though many brokers impose 30%–40% on concentrated or volatile holdings. This calculator finds the exact share price that triggers the call, how much cash you would need to deposit to cure it, and how far the price can fall before you are forced to sell.
Scenario: You buy 2,000 shares at $50 = $100,000 of stock, putting up $50,000 cash and borrowing $50,000 (the Reg T 50% initial requirement). Maintenance margin is 25%.
Current equity: $100,000 − $50,000 = $50,000, which is 50% of market value — well above the requirement.
Call price: The formula solves for the price P where (2,000 × P − 50,000) ÷ (2,000 × P) = 0.25 → P = $33.33.
Interpretation: The stock can fall from $50 to $33.33 — a 33.3% decline — before your broker issues a call. That is your real risk buffer, and it is much larger than most leveraged investors assume.
Scenario: Same 2,000 shares at $50, same $50,000 loan, but the broker applies a 40% maintenance requirement because the position is concentrated in one volatile stock.
Call price: Solving (2,000P − 50,000) ÷ 2,000P = 0.40 gives P = $41.67.
Difference: The call now triggers on a decline of only 16.7%, versus 33.3% at 25% maintenance. A higher house requirement roughly halves your buffer without changing your loan at all.
Takeaway: Always check your broker's actual house maintenance requirement on the specific security — it is often higher than the FINRA 25% minimum, and it can be raised at any time without your consent.
Scenario: The stock falls to $40. Your 2,000 shares are worth $80,000 and you owe $50,000, so equity is $30,000 — 37.5% of market value. That is above 25%, so no call yet. Now suppose it falls to $32, dropping equity to 21.9% — a call.
Cash cure: You need equity ≥ 25% of $64,000 = $16,000. Current equity is $14,000, so a deposit of about $2,000 cures it.
Sell cure: Selling shares and applying the proceeds to the loan reduces both the market value and the debt. Because equity stays the same but the denominator shrinks, the required sale is larger — roughly $2,667 of stock at $32 per share, about 84 shares.
Takeaway: Depositing cash is the cheaper cure for a given call because selling also reduces the asset base that supports your equity. Selling also locks in losses and can trigger a taxable event.
When you open a leveraged position, two separate requirements apply at two different times:
Because the initial requirement (50%) is double the maintenance floor (25%), you have a built-in buffer at the start: the position can fall substantially before maintenance becomes binding. That gap is why a freshly opened 2:1 position tolerates a one-third decline before anyone calls.
FINRA Rule 4210 sets the 25% floor for listed equities, but it explicitly permits brokers to impose higher house requirements and to raise them without advance notice. In practice:
| Position type | Typical maintenance requirement |
|---|---|
| Listed, liquid large-cap equity (long) | 25% — the FINRA floor, used by many discount brokers |
| Most full-service and retail brokers | 30%–35% house requirement |
| Concentrated or low-float positions | 40%–50%, or restricted entirely |
| Pattern day trader accounts | 25% intraday, but $25,000 minimum equity required |
| Short positions | 30% minimum (Rule 4210), often 40%+ house |
| Concentrated positions over 60% of account | Broker-specific; many impose 50% or refuse the position |
This is the single most under-appreciated margin risk. Your broker can change the maintenance requirement on a security — or on your whole account — at any time, and the change takes effect immediately. A position that was comfortable at 25% maintenance can be called the same day the requirement rises to 40%.
One important nuance: brokers are not required to give you a margin call at all. Selling on margin is a contractual right in your margin agreement, and a broker can liquidate to protect itself without notice. The "call" is a courtesy, not a legal entitlement.
Margin interest is charged on the debit balance and compounds daily — it is not a one-time fee. Broker margin rates commonly range from about 5% to 12% annualized depending on the balance (with discount brokers at the high end, and negotiated rates far lower at larger balances). That interest:
Most important: leverage magnifies both directions. A 2:1 position turns a 10% gain into a 20% gain on equity — and a 10% loss into a 20% loss. The margin call is simply the mechanism that makes sure the broker gets repaid before its collateral runs out.
⚠️ Important Disclaimer: This margin call calculator provides planning estimates and is not investment, tax, or legal advice. Maintenance margin requirements vary by broker and by individual security, may be raised without notice, and this tool models only a single long equity position — it does not account for multi-position portfolio margining, option assignments, short positions, pending settlements, or intraday house calls. Margin interest accrues daily and changes your equity continuously, so the call price computed here will drift. Trading on margin can result in losses exceeding your original deposit, and brokers may liquidate positions without prior notice. Confirm your actual maintenance requirement and buying power with your broker before making leveraged decisions.