Futures Margin, Explained Properly

Ask a new futures trader what margin is and you will usually get some version of “the money you put down to buy the contract.” That answer is not slightly off. It is a different concept from a different market, and almost every avoidable account failure in retail futures starts with it.

Margin on a stock is a loan. You borrow to own more shares than your cash allows, and you pay interest on the borrowing. Futures margin is not a loan and there is nothing to borrow, because you are not buying anything. You are entering an agreement, and the exchange wants collateral that you will honour it.

It is a performance bond, and the exchange calls it that

CME Group’s own term is performance bond, which is a considerably more honest name than “margin”. The exchange describes it as a good-faith deposit to guarantee a market participant’s performance against potential future losses on open positions. Nothing is purchased and no money is lent, so no interest is charged on the deposit. A sum is posted as security and it is returned when the position is closed. (That is separate from the financing cost embedded in a futures price itself, which is paid at each quarterly roll rather than billed to you.)

That distinction has a practical consequence worth stating plainly: the performance bond tells you nothing about your risk. It is the exchange’s estimate of what could go wrong in the near term, sized to protect the clearing house, not you. Your risk is the notional value of what you control — which the contract value calculator will work out for any contract in a few seconds, and which is usually a number ten to fifty times larger than the deposit, depending on the contract.

Initial and maintenance: the pair almost everyone conflates

There are two levels, and they do different jobs.

• Initial performance bond — what you must have to open the position.
• Maintenance performance bond — the minimum you must keep in the account while it is open.

Maintenance sits below initial. For speculative accounts — which is every retail account — the buffer at CME Clearing is currently 10%, with the clearing house free to widen it. Member and hedger accounts are set at maintenance with no buffer at all. And here is the part that matters when things go wrong:

The call is issued when equity falls below maintenance — and it must be met back up to initial.

Not back up to maintenance. Back up to initial. So the moment you are called, the amount required is larger than the gap that triggered it. Traders who have only ever read the word “margin” as a single number are consistently surprised by this, usually at the worst possible time.

Variation margin: you are settled every single day

A futures position is marked to market daily. At least twice a business day — an intraday cycle and an end-of-day cycle — the clearing house calculates the change in value of every open position and moves cash accordingly: losers pay, winners are paid. That flow is variation margin, and it is real money leaving or entering your account every day the position is open.

This is why an unrealised loss on a futures position is not a paper loss in the way an unrealised loss on a share is. On a share, nothing happens until you sell. On a future, the money has already moved. The position does not need to be closed for the loss to be funded — it needs to be funded every evening, whether you close it or not.

Day-trade margin is a broker product, not an exchange rule

This is where the most expensive misunderstandings live. The exchange publishes one requirement. Many brokers offer a far smaller intraday or day-trade requirement — sometimes a small fraction of the exchange figure — on the condition that the position is flat before the session close.

Two things follow, and both are worth reading twice.

The intraday number is the broker’s risk appetite, not the exchange’s. It can be withdrawn, and brokers routinely raise requirements before major events or in volatility, sometimes with very little notice.

The requirement reverts at the close. A position opened comfortably on intraday margin and carried overnight is suddenly measured against the full exchange requirement. If the account cannot meet it, the position is liquidated — not because it was wrong, but because it was carried past a deadline. A trader sized against the intraday number has been sizing against a figure that expires daily.

A margin call is not a phone call

The cultural image is a broker ringing to give you a chance to sort things out. In futures, the account agreement you signed almost certainly gives the broker the right to liquidate positions without prior notice when the account is under-margined. Many will do exactly that, automatically, in seconds.

Which is the real lesson of the whole subject: at the point where margin becomes relevant, you have already lost control of the position. Someone else now decides when and at what price it closes, and they will not be choosing the moment to suit you.

How the requirement is calculated, and why it moves

The long-standing framework is SPAN — the Standard Portfolio Analysis of Risk — used by more than fifty exchanges and clearing organisations worldwide. Rather than applying a flat percentage, it revalues a portfolio across an array of scenarios (price up and down by defined amounts, volatility shifts, time decay) and sets the requirement from the worst plausible outcome. It also nets offsetting positions, which is why a calendar spread requires far less than two outright contracts.

CME is migrating products to a successor, SPAN 2, and this matters for the instruments most of this site is about: energy and equity index products — including the E-minis and Micro E-minis — are already on it, with interest rates and FX scheduled. SPAN 2 uses filtered historical value-at-risk plus stress scenarios rather than a fixed scenario array. The practical consequence for a retail trader is the same in both: the requirement is derived from risk, so it moves.

The consequence is that margin rises when volatility rises. Not as punishment; the scenarios simply got wider. But note the timing: requirements go up in exactly the conditions that make positions uncomfortable, so the demand for more collateral tends to arrive on the day you least want to fund it. Every trader who has read the 1980 silver story knows how far that can be taken — measured from the start of the run in mid-1979, margin on a silver contract rose roughly thirtyfold, and the thesis behind the position never changed at all.

Because the numbers move, this site never publishes them. Take today’s figure from your broker or from the exchange’s own performance bond page, and re-check it before any scheduled event.

The four sentences worth memorising

• Margin is not the size of your trade. Notional value is. Margin is a deposit against it.
• Margin is not your risk. Your risk is your stop distance multiplied by the contract’s value per point, multiplied by contracts.
• Margin is not a limit on your losses. Nothing prevents a loss exceeding the deposit; you owe the difference.
• “I can afford the margin” is not a position-sizing method. It is how accounts end up at twenty-five times leverage without anyone deciding to be.

The sizing question has an actual answer, and it runs the other way round: decide what you are willing to lose, decide where the trade is wrong, and let those two numbers produce the contract count. That is what the position size calculator does, and the margin requirement never enters into it — it only tells you whether the broker will let you place the order at all.

Where to go next

The companion piece on the other side of the same arithmetic is the contract and leverage calculator, which turns the same specs into notional value and leverage. For what the options market does with margin-derived levels, see options positioning. And for what happens when a correct thesis meets a margin department, the Hunt brothers remain the definitive case.