Overnight Margin
The full exchange-minimum initial margin required to carry a futures position through the close into the next session.
Overnight margin is the margin required to hold a futures position past the broker's daily cutoff time — typically 15–30 minutes before the session close. It equals or exceeds the CME's published initial margin and is higher than the reduced day-trading rate.
Carrying futures overnight exposes the account to gap risk: if the underlying gaps sharply on news (FOMC, CPI, earnings), the loss can exceed the available margin before the trader has a chance to exit. Most scalpers avoid overnight holds for exactly this reason.