SEC Greenlights Boring Stock Market Closing Auction Tweaks
Published Date: 9/9/2025
Notice
Summary
Cboe BZX Exchange is updating its rules for the Closing Auction, changing how certain orders (LLOC and LOC) are priced and when traders can enter, change, or cancel them. This affects traders using these special order types and aims to make the closing price fairer and clearer. The new rules kick in soon with no extra costs, helping everyone wrap up trading smoothly at 4 p.m. each day.
Analyzed Economic Effects
4 provisions identified: 2 benefits, 1 costs, 1 mixed.
LLOC submission earlier; no cancels after entry
Users (including Lead Market Makers) may begin submitting LLOC orders at 3:55 p.m. ET instead of being blocked before 3:59 p.m., but once an LLOC order is entered it may not be modified or cancelled; LLOC orders will continue to be accepted until 4:00 p.m. ET.
LOC re‑pricing to 3:55 Reference Price for corporate listings
For BZX-listed corporate securities, an LOC order entered between 3:55 p.m. ET and 3:59 p.m. ET will be accepted at its limit price unless the limit price is higher (for buy orders) or lower (for sell orders) than the 3:55 p.m. Reference Price; in those cases the LOC will be re-priced to the 3:55 p.m. Reference Price. If no Reference Price is available, the LOC keeps its user-entered limit price. LOC orders in BZX-listed ETPs will not be re-priced.
LLOC orders may be re‑priced both ways
If you use Late-Limit-On-Close (LLOC) orders, the Exchange will now allow those orders to be re-priced to both more aggressive and less aggressive prices so long as the adjusted price does not exceed your original user-entered limit price. If there is no National Best Bid (NBB) or National Best Offer (NBO) when the order is received, the LLOC will assume its entered limit price; if the NBB/NBO becomes unavailable after an adjustment, the LLOC keeps its last adjusted price until the NBB/NBO is available again.
LOC orders cannot be changed 3:55–3:59 p.m.
While Limit-On-Close (LOC) orders may be submitted up to 3:59 p.m. ET, the Exchange will prohibit modifying or cancelling any LOC orders between 3:55 p.m. ET and 3:59 p.m. ET regardless of when the LOC was originally received.
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