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Opening and Closing Auction Times

Opening Auction Times

  • 8:00 a.m. - The Cboe Pre-market Trading session begins. Dissemination of Opening Auction information begins.

  • 9:28 a.m. - MOO/LOO orders are cutoff and LLOO orders are accepted at this time.

  • 9:30 a.m. - The Opening Auction Match occurs.

Delayed Opening Auction (Effective 10/05/26)

If at 09:30:00 a.m. the midpoint of the NBBO cannot be used as the opening auction collar reference price, then the collar range set by the Final Last Sale Eligible Trade (FLSET) will be compared to the current auction Indicative Price. If the Indicative Price is outside the established collars, the opening auction will be extended. If the Opening Auction is extended, Auction Update messages will continue to be disseminated every 5 seconds after 09:30 a.m.

In the case the opening auction is extended, the auction will be re-tried at the following times:

  • 09:30:01 a.m.

  • 09:30:02 a.m.

  • 09:30:03 a.m.

  • 09:30:04 a.m.

  • 09:30:05 a.m.

At each of the above times, the opening auction collars will be re-evaluated based on changes to the NBBO or on trades occurring after 09:30:00 a.m. which allow a new collar reference price to be established. If the NBBO is valid or if the Indicative Price falls within the opening auction collars set by the FLSET, then the opening auction will be conducted.

If the FLSET is still being used as the collar reference price and the Indicative Price is still outside of the established auction collars at 09:30:05 a.m., then the opening auction will be further extended. At 09:30:05 a.m., the upper or lower opening auction collar price will be widened by an amount that is 5% of the FLSET towards the Indicative Price at periodic time intervals until the Indicative Price is within the collars or the maximum number of extensions is exhausted. If at any time the Indicative Price is within the collars, the opening auction will be conducted.

Additionally, if at any time there is no crossing interest in the auction, the security opens immediately using the FLSET as the opening price.

The 5% widening of the upper or lower opening auction collar will occur at the following times:

  • 09:30:05 a.m.

  • 09:30:30 a.m.

  • 09:31:30 a.m.

  • 09:32:30 a.m.

  • 09:33:30 a.m.

  • 09:34:30 a.m.

At 09:34:30 a.m., the opening auction will conclude using the opening auction collars present at that time.

Should the opening auction be extended, the following eligible order types will be accepted after 09:30:00 a.m.:

  • Continuous book orders

  • Regular Hours Only limit orders (treated as Late-Limit-On-Open (LLOO) orders)

  • LLOO orders (treated in the same manner as LLOO orders between 09:28:00 a.m. and 09:30:00 a.m.)

Closing Auction Times

  • 3:00 p.m. - Dissemination of Closing Auction information begins.

  • 3:55 p.m. - MOC orders are cutoff at this time. LOC orders in Corporate Listings entered after this time are capped to the 3:55 p.m. Reference Price. LOC orders in all securities cannot be cancelled or modified. LLOC orders are accepted at this time.

  • 3:59 p.m. - New LOC orders are cutoff at this time.

  • 4:00 p.m. - The Closing Auction Match occurs.

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