Unscheduled Market Closings Guide
The Options Clearing Corp (OCC) has issued updated guidance on their website. Here is the direct link: https://www.theocc.com/components/docs/about/publications/unscheduled-market-closings-guide.pdf
Of note:
Equity and ETF Options
If an outage or other event at either an underlying or option exchange prevents OCC from obtaining a closing price for a product, OCC will apply OCC Rule 805 in assigning a settlement price. OCC Rule 805 permits the use of the last available sale price during regular trading hours on the most recent trading day for expiration processing for equity and ETF options.
Market Wide Circuit Breaker
In the event that an intra-day Market Wide Circuit Breaker (MWCB) of 20% is triggered so that trading is halted for the remainder of a trading day, it is anticipated that the SOQ settlement price from the next trading day following the closure will typically be used for expiration processing for p.m. settled index products.