What a margin call actually is, procedurally

A call is not a warning. It is a demand with a clock, and sometimes the clock is zero.

The phrase margin call suggests a phone ringing. Procedurally it is closer to a status change in a system, which may or may not produce a phone call, and which may or may not wait for you to answer it.

The sequence, stripped down: the lender revalues collateral, usually daily and sometimes intraday. It applies current advance rates to produce lending value. It compares your balance to the threshold. If the threshold is breached, the account is flagged. From that moment the lender has a contractual right to require additional collateral, require repayment, or sell pledged securities.

What happens next varies, and the variation is the part worth knowing:

Some agreements provide a cure window — a stated number of business days to post collateral or repay.
Many agreements also reserve the right to act immediately, without notice, when markets are moving fast.
Notice, where it exists, is often described as a courtesy the lender may extend rather than an obligation it must meet.
The lender usually chooses which positions to sell, not you.

Two details cause the most damage. First, the cure window and the right to act without notice frequently coexist in the same document, so the existence of a stated window is not a guarantee that you will get it. Second, the lender's revaluation runs on live prices while your view of your own position may be a statement from three weeks ago. The gap between those two clocks is where surprise lives.

Key terms

Margin call: A demand, triggered by a breached threshold, to post additional collateral or repay part of the loan.
Cure window: A stated period in which a borrower may fix a shortfall before the lender sells. Often present, rarely guaranteed.
Liquidation discretion: The lender's right to choose which pledged securities to sell, in what order, and at what time.

Worked example

The mechanics of one call

Balance $300,000, threshold 70% of market value, market value falls from $600,000 to $410,000.

LTV after the fall: 73.2%
Threshold: 70%
Balance permitted at $410,000: $287,000
Shortfall to cure by repayment: $13,000
Alternative: collateral to post: $18,571

A 31.7 percent market decline produced a $13,000 demand. The demand is small; the problem is that curing it by selling is not the same size, which is the next lesson.

Check yourself

Your agreement states a three-business-day cure window and also reserves the right to sell without prior notice. Which applies?

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Educational only. Nothing in this lesson is investment, legal or tax advice, or a recommendation to enter into any transaction. Figures are illustrative and computed from the inputs stated in the lesson.