Cboe Regulatory Circular 26-007 confirms a market-structure change that matters more for fills than forecasts: as of April 27, 2026, Cboe Options and EDGX Options removed prior restrictions that had prevented an appointed Market Maker from being paired as the solicited contra-side order in certain AIM and SAM auctions.
This is market context and options education only. It is not financial advice, investment advice, trading advice, or a recommendation to buy or sell anything. Options trading involves risk and is not suitable for all investors. See the site’s Risk Disclosure.
What changed (confirmed facts)
The circular and related SEC materials describe the change as an eligibility update for the initiating contra in specific auction types:
- Cboe Options: appointed Market Makers can be solicited as contra in simple AIM, simple SAM, FLEX AIM, and FLEX SAM auctions (effective April 27, 2026).
- EDGX Options: appointed Market Makers can be solicited as contra in simple AIM and simple SAM auctions (effective April 27, 2026, per the circular’s effective date).
- Complex auctions are not the novelty: the circular states appointed Market Makers were already not restricted from serving as contra in complex AIM and complex SAM auctions.
Nothing about this change alters option contract terms, settlement, exercise/assignment mechanics, or how implied volatility is calculated. The “action” is in order handling and auction participation rules.
AIM vs SAM in plain English (why most retail-sized orders care more about AIM)
Both AIM and SAM are price-improvement auction mechanisms. The initiating firm submits a customer order plus a paired contra-side order, and the auction exposes the order to competition for a brief time window.
The practical difference for many self-directed traders is simple: AIM is commonly relevant to smaller, single-leg orders, while SAM is designed for larger orders. Cboe materials describe SAM as having a minimum size threshold (commonly cited as 500 contracts), which pushes it out of “typical retail” territory for many traders.
If you want a glossary refresher for market-structure terms that show up in filings (NBBO, midpoint, internalization, etc.), start here: Options trading terminology: a beginner-friendly glossary.
Why this matters for options traders (interpretation, not a guarantee)
Think of the change as widening the set of firms that can supply the guaranteed initiating liquidity that starts an auction. That can matter in a few ways:
1) It can change how easily auctions get launched
If more entities are eligible to be the solicited contra, it can be operationally easier for routing firms to initiate an auction for an eligible order. In practice, that can increase the chance your order is routed into a price-improvement auction rather than being handled purely in the continuous market.
That said, “more auctions” is not the same as “better fills.” Outcomes still depend on:
- how competitive the responses are at the winning price,
- how the broker routes your order (and when),
- whether your order is auction-eligible in the first place,
- market conditions (spreads widen and liquidity thins under stress).
2) The benefit (if any) shows up in realized trading cost, not headlines
This is not an expected-move or “IV should rise/fall” story. The most defensible “signal” is in the difference between:
- quoted prices (displayed spreads), and
- effective outcomes (your realized execution price relative to the market at that moment).
If the change helps at the margin, it shows up as slightly better execution inside the spread on some orders, not as a clean shift in implied volatility, skew, or a directional forecast.
3) Routing and conflicts still matter (and the safeguards still exist)
The circular emphasizes that anti-circumvention controls remain in place, including restrictions tied to EFIDs (the initiating contra and a response cannot be the “same EFID” participant) and reminders about procedures and information barriers.
In other words: the exchange expanded who can be the solicited contra in certain auctions, but it did not remove the idea that auction integrity depends on participation constraints and supervision.
Common misunderstandings (and caveats)
- “This guarantees price improvement.” No. Auctions can improve execution, but nothing in the rule change guarantees better fills on every order.
- “This should tighten spreads across the market.” Not necessarily. Auction improvements can occur inside the spread without changing displayed quotes.
- “This changes complex spread auctions.” The circular indicates the complex-auction restriction was not the focus; the novelty is in the simple auction eligibility.
- “This is bullish or bearish.” It’s execution plumbing. Treat it as market-structure context, not a directional signal.
Practical takeaways (no trade recommendations)
If you care about execution quality, this circular is a reminder to make order handling part of your process:
- Prefer intentional order types. Many traders default to market orders in fast conditions; that can be expensive in options. Review basics in Common options trading mistakes (and how to avoid them).
- Compare fills to a sensible benchmark. “Did I get the midpoint?” is often more informative than “did I get filled?” (especially in wide markets).
- Read your broker’s routing disclosures. Rule 606-style reporting and broker disclosures can help explain where orders are going and why price-improvement venues matter.
- Treat execution as risk management. Slippage is a risk input, not an afterthought. If you’re revisiting process, start with Risk management in options trading: position sizing and probability.
Bottom line
Cboe Circular 26-007 describes a targeted change: as of April 27, 2026, appointed Market Makers can be solicited as the initiating contra in additional simple AIM/SAM auctions (plus certain FLEX auctions on Cboe). The clean way to read it is “execution-quality plumbing.” It may expand auction access at the margin, but it does not guarantee better fills, and it is not a directional market tell.
This article is for general information and education only. It is not financial advice, investment advice, or trading advice. Options trading involves risk and is not suitable for all investors.
Sources
- Cboe Regulatory Circular 26-007 (effective date, scope, anti-circumvention reminders):
https://cdn.cboe.com/resources/regulation/circulars/regulatory/RC26-007-Appointed-Market-Maker-Contra-Parties-in-AIM-and-SAM-Auctions.pdf - SEC approval order for SR-CBOE-2025-090 (Cboe rule change context, rationale):
https://www.sec.gov/files/rules/sro/cboe/2026/34-105049.pdf - Federal Register notice for SR-CboeEDGX-2026-021 (EDGX filing details and immediate effectiveness notice):
https://www.federalregister.gov/documents/2026/04/22/2026-07821/self-regulatory-organizations-cboe-edgx-exchange-inc-notice-of-filing-and-immediate-effectiveness-of - SEC exhibit with EDGX rule text (what changed in the EDGX rules):
https://www.sec.gov/files/rules/sro/cboeedgx/2026/34-105273-ex5.pdf - Cboe “Crossing Orders” overview (AIM/SAM operational description):
https://www.cboe.com/us/options/trading/crossing_orders/ - Cboe C1 Exchange Rule Book PDF (definitions and rule references):
https://cdn.cboe.com/resources/regulation/rule_book/C1_Exchange_Rule_Book.pdf - SEC proposed Regulation Best Execution release (broader context on options order routing and internalization):
https://www.sec.gov/files/rules/proposed/2022/34-96496.pdf
