> The second cash sweep that will happen actually happens overnight. You will see this listed as "Cash Sweep" in ThinkorSwim. This overnight sweep is used to get the futures cash balance high enough to cover the exchange's initial requirement which is posted by the CME. As of today, for /MES the exchange initial requirement is 2,412.3 per contract for longs, however this does change every day. The overnight sweep moves the cash, so the futures cash balance equals the exchange initial requirement.
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Explanation from Interactive Brokers:
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> The settled cash in both segments are summed when computing principal subject to interest, and the margin requirements for the futures are then backed out.
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> Principal is per currency and = total settled cash - short stock collateral - futures margin
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Forum threads:
- [How do rolling and margin on futures trading work?](https://www.bogleheads.org/forum/viewtopic.php?t=300111)