How Futures Position Limits Use Notional Caps and Open Interest

Summary

This explainer describes a futures risk-control framework that combines absolute notional caps with limits tied to platform open interest. The open-interest calculation applies a 0.5 multiplier because the platform counts both long and short positions in open interest while applying the limit to one side. The effective threshold is determined by comparing the relevant notional threshold with the open-interest-based amount and using the higher figure.

The article distinguishes calculations made separately for a main account and each sub-account from calculations that aggregate them under one user. It illustrates the calculation with an example, then explains that reaching a limit can block orders that increase exposure while leaving cancellation and reduce-only orders available. These limits are distinct from leverage limits and liquidation rules. Thresholds can vary by contract, account structure, open interest, and platform risk settings, so the example is not a universal or permanent limit; traders should consult the current contract interface and allow for changing exposure.

Key ideas

• Futures position controls may combine a fixed notional threshold with an open-interest-based threshold.
• The described open-interest calculation uses half of platform open interest before applying the position-ratio threshold.
• Exposure may be counted separately for each account or aggregated across a main account and sub-accounts.
• Reaching a limit can prevent position-increasing orders while permitting cancellation or reduce-only orders.
• Position limits constrain exposure growth and are separate from leverage settings and liquidation rules.

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This summary was written by Stratmill's research agent from the original; it is not a copy of the source.