MIAX has posted a pending rule filing (SR-MIAX-2026-22) to add an optional feature called Selective Liquidity Auto Purge (SLAP) to MIAX Options Rule 519C. The short version: a market maker would be able to tag certain Standard quotes with a SLAP code, then selectively purge those quotes (and temporarily block new quotes in that same tagged group) without pulling everything.
This is a market-structure / execution-quality story, not a market call. It doesn’t change option contract terms, OCC exercise rules, or whether a strategy like a covered call “works.” It changes how one venue may let professional liquidity providers manage quoting risk when conditions are moving.
Important Notes (Not Advice + Options Risk)
This article is for general information 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.
Why This Matters For Options Traders
Even if you never trade on MIAX intentionally, changes to quote-management controls matter because:
- Displayed liquidity can vanish in targeted chunks. In fast conditions, a selective purge can remove a specific subset of quotes by design, which can widen spreads and make “the chain” look jumpy.
- Execution quality is path-dependent. When quotes thin out, fills can get worse and implied volatility readings can get noisier. If you use “expected move” or IV as context, it helps to remember those numbers are derived from quotes that can change quickly. Refresher: Implied volatility (IV) in options trading.
- The effect is not uniform across strikes/expirations. A tool like SLAP is designed to be granular, which is good for risk control - but it also means certain pockets of liquidity can disappear while others remain.
Treat this as an execution-mechanics update: more about “how quotes behave under stress” than about “what direction the market will go.”
What SLAP Is (Confirmed Mechanics)
Based on MIAX’s filing description:
- SLAP applies to Standard quotes submitted via the MIAX Express Interface (MEI).
- A market maker can tag Standard quotes with a SLAP code (codes 1 through 8).
- A “selective purge” message can be keyed to MPID + underlying + SLAP code.
- Matching Standard quotes are removed.
- New inbound matching Standard quotes are blocked until a SLAP reset is submitted (the filing describes matching quotes as rejected until reset).
- eQuotes are not eligible for SLAP coding under the proposal.
The practical difference versus a blunt “pull everything” control is the ability to segment quotes into buckets (by code) and then shut off only the bucket that’s risky in the moment.
What SLAP Is Not
It’s easy to overread exchange filings. SLAP is not:
- A promise of tighter spreads or better fills.
- A guarantee that liquidity will remain stable in a fast market.
- A new “signal” about where a stock or index is going.
- A change to assignment/exercise mechanics.
It’s a risk-control lever for liquidity providers on one venue.
Why an exchange would want a more granular purge tool (Interpretation)
Modern listed options markets involve extremely large quote and message volumes, and market makers often maintain large grids of quotes across strikes and expirations for a single underlying. In fast markets, the risk is that quotes go stale faster than they can be updated, which can create outsized losses for the quoting firm.
There are two broad paths a venue can encourage:
- All-or-nothing protection: market makers use broad kill switches and withdraw liquidity aggressively when they’re uncertain.
- More granular protection: market makers can remove only the subset of quotes that is most likely to be stale (or most exposed), while keeping other quotes live.
SLAP is an attempt to make path (2) easier. The trade-off for public traders is that “the quotes you wanted” can disappear selectively during the very windows when everyone is trying to trade.
If you want a plain-English reminder of why spreads matter more than most people assume, see Options volume vs open interest: how to read market activity (liquidity basics) and How earnings affect options prices and implied volatility (market-maker risk and spread-widening context).
Timeline and status language (Avoid the common confusion)
One of the most frequent misunderstandings with exchange filings is mixing up:
- Filed / proposed (a rule change has been submitted),
- Pending (not yet fully through the process / not yet live),
- Effective (a regulatory status that does not necessarily mean “implemented in production today”), and
- Implemented (actually live for trading/quoting).
MIAX’s materials describe SR-MIAX-2026-22 as a pending filing, and the proposal discusses a targeted Q3 2026 implementation window with advance notice via Regulatory Circular. The safest reader takeaway is: MIAX proposed SLAP; it is not something retail traders should assume is active everywhere today.
Common Misunderstandings
- “SLAP is a retail protection feature.” It’s primarily a market-maker risk-control tool. Retail can benefit indirectly if it helps maintain some quote continuity, but it can also mean certain quote buckets disappear more cleanly in fast conditions.
- “Once purged, quotes automatically resume.” Under the proposal, matching inbound Standard quotes are blocked/rejected until a SLAP reset is submitted.
- “It applies to all MIAX quotes.” The filing describes eligibility for Standard quotes submitted via MEI; eQuotes are not eligible for SLAP coding.
- “This means MIAX expects a volatility event.” There’s no need to treat this as directional. It’s better understood as one venue evolving its quote-risk controls.
Bottom line
SR-MIAX-2026-22 proposes SLAP as a more granular way for MIAX Options market makers to purge (and temporarily block) specific groups of Standard quotes using MPID + underlying + SLAP code. For options traders, the practical point is execution context: in fast markets, targeted liquidity can disappear by design, which can widen spreads and make displayed IV and “expected move” style context noisier.
Sources
- MIAX rule filings page (SR-MIAX-2026-22 listed as a pending filing):
https://www.miaxglobal.com/rule-filings- Used to confirm the filing identifier, date, and “pending” status as posted by MIAX.
- SR-MIAX-2026-22 (proposed Rule 519C changes describing SLAP mechanics, including MPID/underlying/code keys, blocking until reset, and eQuote eligibility):
https://www.miaxglobal.com/sites/default/files/filing-files/SR_MIAX_2026_22.pdf- Used for the feature description and operational constraints.
- MIAX interface specification update / technical alert (MEI/AIS/FOI spec updates referencing SLAP support):
https://www.miaxglobal.com/alerts- Used for context that technical specs were updated to support the enhancement ahead of an activation date.
