The full exchange-set margin that applies to any futures position still open at the end of the session.
Brokers offer discounted intraday rates, but at a published cutoff — often shortly before the daily close — every open position is re-checked against full initial-margin. Accounts that cannot cover are liquidated, sometimes automatically and sometimes into thin after-hours markets.
Traders who size by day margin and "decide later" whether to hold overnight regularly discover this the hard way.
Example: a $3,000 account holding four MNQ contracts on $100 day margin is fine at 4pm and short by thousands at 4:59pm if overnight margin is $2,000 per contract.
Original diagrams for the ideas on this page. Illustrative, not real market data.
Margin and leverage. A $5,000 deposit can control a $100,000 position, which is 20:1 leverage. Because the loss is measured on the full $100,000, a 2.5% move against you halves the deposit and brings a margin call, and a 5% move uses all of it.
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