MIAX Tweaks Rules for Closed Market Trading Days
Published Date: 4/14/2025
Notice
Summary
MIAX is updating its rule to use the last sale price from the previous day when the main market doesn’t open, so index options can still be priced fairly at expiration. This change affects traders using MIAX’s index options and kicks in immediately, helping avoid confusion or delays on unusual market days. No extra costs are expected, just smoother trading when markets act up!
Analyzed Economic Effects
3 provisions identified: 3 benefits, 0 costs, 0 mixed.
Use Prior Day Price at Expiration
When the primary market for an index component does not open on an options expiration day, MIAX will use the last reported sale price from the previous trading day to calculate the index settlement value at expiration. This change became operative upon filing on March 27, 2025 and is intended to give traders certainty and avoid delays or confusion on unusual market days.
Applies to A.M.-Settled Index Options
At the time of the filing, the amended rule applies only to A.M.-settled index options (the traditional third-Friday A.M. settlement). The Exchange states that if related rule SR-MIAX-2025-08 is approved, the provision would also apply to P.M.-settled index options for the B500 Index.
Also Applies to MIAX Affiliate Members
The amendment to Rule 1808(g) is incorporated by reference into the rulebooks of MIAX affiliates MIAX Pearl, MIAX Emerald, and MIAX Sapphire, so members of those exchanges will be subject to the same pricing procedure when a primary market fails to open. The Exchange noted the change will apply uniformly to all Members.
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