Initial Margin vs Variation Margin

Open a futures position and two very different pots of money start moving. One is a deposit sitting untouched, there in case things go badly. The other changes hands every single day, win or lose, before anyone knows how the trade will end. Beginners often lump both under "margin" and get confused about why they need to post more money when the trade hasn't even lost yet. The two pots answer different questions, and keeping them separate is the whole trick.

Initial margin: the deposit against the future

Initial margin (IM) is collateral posted before a position can be opened. It is not a payment for anything that has happened, it is a buffer sized to cover a plausible bad day. A clearinghouse or broker estimates how much the position's value could move against you over a short horizon, typically one to a few days, at a high confidence level, and asks for that much upfront.

Concretely, IM is close in spirit to a Value at Risk (VaR) number: "how much could this position lose, with 99% confidence, before we can react and close it out." The exact figure depends on the asset's volatility, the position's size, and the horizon assumed — a volatile single stock future demands far more IM per dollar of exposure than a Treasury future.

Variation margin: settling today's move

Variation margin (VM) is different in kind. At the end of each trading day, the exchange marks every open position to that day's closing price and settles the difference in cash. If your futures position gained $3,000 today, $3,000 lands in your account, debited from whoever is on the other side. If it lost $3,000, that amount leaves your account and goes to them. This is mark-to-market settlement, and it happens whether or not you plan to close the trade.

The consequence is that a futures position never accumulates a large unrealized loss the way a stock position can. Every loss is paid out daily, in cash, immediately. That is precisely why exchanges can offer high leverage safely: nobody's exposure to a counterparty's unpaid losses ever grows past one day's move.

Worked example

You open one crude oil futures contract (1,000 barrels) at $80. The exchange sets initial margin at $5,000, roughly covering a bad single-day move.

• Day 1: price falls to $78. Loss of $2 per barrel on 1,000 barrels = $2,000 variation margin, debited from your account today.
• Day 2: price falls further to $76. Another $2,000 debited.
• Day 3: price rebounds to $79. You gain $3 per barrel on 1,000 barrels = $3,000 credited back.

Across the three days you paid out $4,000 and received $3,000 net, exactly tracking the price path. Your initial margin of $5,000 never moved — it just sat there as the buffer the exchange is relying on if you can't pay a variation margin call. If your account's cash falls below what is needed to keep posting VM, you get a margin call; see Margin Calls and Forced Liquidation for what happens if you can't meet it.

Where this matters beyond futures

Since post-2008 reforms, the same two-pot structure was extended to most standardized OTC derivatives via central clearing, and increasingly to bilateral (non-cleared) swaps under uncleared margin rules. A bank facing another bank in an interest rate swap now posts both IM and VM, exactly mirroring the futures mechanism, precisely because regulators wanted to shrink the uncollateralized exposure that firms like Lehman Brothers left on other institutions' books. This is a direct thread into Counterparty Credit Risk: VM shrinks the loss if a counterparty defaults today, while IM covers the gap between default and the time it takes to close out the position.