Cboe Speeds Up Auction Responses: Faster Trades, Same Old Rules
Published Date: 3/30/2026
Notice
Summary
Cboe Exchange is updating how it handles auction responses to speed things up and make trading smoother for investors and traders. The Securities and Exchange Commission quickly approved these changes, which will take effect soon and could help markets work better without extra costs. This update mainly affects people using Cboe’s auction system for certain types of trades.
Analyzed Economic Effects
4 provisions identified: 3 benefits, 1 costs, 0 mixed.
Non‑FLEX auctions: 1‑second processing cap
If you submit responses to Cboe non‑FLEX option auctions, the Exchange may now allow the auction exposure period plus post‑auction processing to run up to 1000 milliseconds (1,000 ms) total. The change lets the system continue processing messages received before the auction end for a longer buffer so more timely responses may be included in the auction.
SPX non‑FLEX: 900 ms buffer made permanent
For non‑FLEX SPX options, the longer auction response processing time that had been set to 900 milliseconds will be preserved on a permanent basis. Previously that 900 ms setting was in place under a temporary/sunset schedule (noted in the filing as in place until June 30, 2026).
Potential for more price improvement and liquidity
The Exchange says the longer processing buffer may let more auction responses participate, which could increase execution opportunities and price improvement for auctioned orders and may encourage liquidity providers to submit more responses, deepening auction liquidity. The filing ties these benefits to times of high message traffic and volatility.
FLEX auctions excluded from increase
FLEX auctions (FLEX Auction Process, FLEX AIM, and FLEX SAM) are excluded from the longer auction response processing time and will continue to operate under their existing longer exposure periods. The Exchange said FLEX auctions did not show missed responses and have different liquidity and timing needs.
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