Updated for the 2026-2027 CFA® Level I curriculum.
Margin transactions let an investor buy securities partly with borrowed money. Borrowing changes three things: how much cash the investor needs upfront, how the return on the position is calculated, and the price level that triggers a broker's demand for more funds. CFA Level I tests whether you can calculate the leverage ratio, the return on a margin transaction, and the margin call price, and whether you understand why leverage magnifies both gains and losses.
Quick Answer
The margin call price is the security price that reduces investor equity to the maintenance margin requirement. The formula is:
where is the original purchase price, is the initial margin requirement, and is the maintenance margin requirement. If the price falls to or below this level, the broker issues a margin call requiring the investor to add funds or sell the position.
Key Takeaways About Margin Transactions: Leverage, Returns, and Margin Calls
The leverage ratio equals total position value divided by investor equity, not by borrowed funds.
A higher leverage ratio means a given price move produces a larger percentage change in investor equity.
Return on a margin transaction adjusts for interest paid on borrowed funds and any dividends received.
The margin call price formula is .
Margin calls are triggered using the maintenance margin requirement, not the initial margin requirement.
Leverage magnifies both gains and losses on the investor's equity investment.
A lower maintenance margin requirement gives an investor more room before a margin call occurs.
What You Need to Know for CFA Level I
Calculate the leverage ratio for a margin position and interpret what it means for risk.
Calculate the investor's rate of return on a margin transaction, including interest cost.
Calculate the security price that triggers a margin call.
Explain how leverage changes the size of gains and losses relative to an unleveraged position.
Leverage Ratio Calculation and Interpretation
The leverage ratio measures how much of a position is funded by the investor's own money versus borrowed funds.
Investor's equity equals total position value minus the amount borrowed. A leverage ratio of 2.0 means the investor's equity funds half the position and borrowed funds fund the other half. A leverage ratio of 1.0 means no borrowing occurred.
The higher the leverage ratio, the smaller the price move needed to wipe out the investor's equity. This is why the leverage ratio is the starting point for both the return calculation and the margin call calculation.
Rate of Return on a Margin Transaction
Return on a margin transaction is calculated on the investor's equity, not on the total position value. Interest paid on borrowed funds reduces the return. Dividends received increase it.
This differs from the price return on the security itself. The price return ignores financing costs and is calculated on the full position value. The return on equity reflects what the investor actually earned on the cash actually invested.
Security Price That Triggers a Margin Call
A margin call occurs when the security price falls enough that investor equity, as a percentage of position value, drops to the maintenance margin requirement.
Where:
= original purchase price
=initial margin requirement
= maintenance margin requirement
As the price falls, the dollar amount borrowed stays fixed, so investor equity shrinks faster than the position value. The margin call price is the exact point where equity as a percentage of position value hits the maintenance margin.
Concept | Formula | Key Notes |
|---|---|---|
Leverage ratio | ||
Return on margin transaction | Use actual interest cost, not the amount borrowed | |
Margin call price | is the original purchase price, not the current price |
How Leverage Changes Gains and Losses
Leverage does not change the dollar gain or loss on the position itself. It changes the percentage return on the investor's equity, because that return is calculated on a smaller base.
As a shortcut, ignoring interest and dividends, the return on equity is approximately the leverage ratio multiplied by the price return:
A leverage ratio of 2.0 roughly doubles both the percentage gain on a price increase and the percentage loss on a price decrease. This is why margin buying increases risk even though it does not change the underlying security.
Worked Example
Setup: An investor buys 200 shares of Larkspur Corp at $50 per share. The initial margin requirement is 50%. The maintenance margin requirement is 25%. The broker charges 4% annual interest on borrowed funds. No dividends are paid during the holding period.
Step 1: Leverage ratio
Step 2: Return after one year, assuming the price rises to $60
The unleveraged price return is . Leverage increased the percentage return even after interest.
Step 3: Margin call price
If Larkspur's price falls to $33.33, the broker issues a margin call because investor equity has fallen to 25% of position value. The price would need to drop by roughly one-third from the purchase price before that happens. Leverage helped the investor earn 36% instead of 20% when the price rose, but the same leverage means a price decline produces a proportionally larger equity loss.
Common Exam Traps
Using total position value instead of investor equity in the leverage ratio
The leverage ratio divides total position value by investor equity, not the reverse, and the denominator is equity, not borrowed funds.
Ignoring interest cost when calculating return
The return on a margin transaction subtracts interest paid on borrowed funds. Skipping this step overstates the investor's actual return.
Using initial margin instead of maintenance margin in the margin call formula
The margin call price formula uses maintenance margin in the denominator. Confusing the two requirements produces the wrong trigger price.
Reversing the direction of leverage's effect
Leverage magnifies both gains and losses in the same direction as the price move. It does not protect against losses or only apply to gains.
Practice Question
An investor buys 400 shares of Doverton Inc at $40 per share on margin. The initial margin requirement is 60%. The maintenance margin requirement is 30%. What is the margin call price?
$17.14
$22.86
$12.00
Correct Answer: B
Calculation:
As the share price falls, the fixed dollar amount borrowed makes up a growing share of position value. At $22.86, investor equity has fallen to exactly 30% of position value, triggering the margin call.
Option A: $17.14 results from swapping the margin percentages, placing maintenance margin in the numerator and initial margin in the denominator.
Option C: $12.00 results from multiplying the purchase price directly by the maintenance margin percentage, skipping the leverage adjustment entirely.
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FAQs About Margin Transactions: Leverage, Returns, and Margin Calls
What happens if the stock price falls below the margin call price?
The broker requires the investor to deposit additional cash or securities, or to sell part of the position, to bring equity back to the maintenance margin requirement.
Does the margin call price change if interest rates change?
No. The margin call price formula depends only on the purchase price, initial margin, and maintenance margin. Interest cost affects the investor's return, not the margin call trigger price.
Is initial margin used anywhere in the margin call price formula?
Yes. Initial margin sets the original equity percentage at purchase, which appears in the numerator. Maintenance margin, which sets the minimum ongoing equity percentage, appears in the denominator.