Nasdaq MRX has filed to add a new fee called the “Historical CAT Assessment 1A.” The fee is part of how the industry funds the Consolidated Audit Trail (CAT), and the first monthly invoice is expected in June 2026 based on May 2026 trading activity.
For most self-directed traders, the direct per-trade dollar amount is very small. The practical relevance is that exchange- and industry-level fees can still show up in your all-in execution costs (for example as a small pass-through line item, or indirectly through route economics and spreads), even if you trade with low or zero commissions.
This article is for market context and options education only. It is not financial advice, investment advice, or trading advice. Options involve risk and are not suitable for all investors.
Why this matters for options traders
Even tiny per-execution fees matter in a few common options-trading contexts:
- High turnover and many legs: If you trade frequent small-lot strategies, the number of executions (and the number of legs) can be the main driver of “invisible” friction.
- Market-wide liquidity costs: A fee assessed on executing brokers also applies to professional liquidity providers. Over time, systematic cost changes can influence quoting economics, which can show up as slightly wider spreads in some products.
- Tracking and attribution: If your broker passes through the fee explicitly (or bundles it into a regulatory-fee line), it can change how you reconcile fills, commissions/fees, and strategy P/L - especially when you are comparing brokers or routes.
What changed (in plain English)
The Nasdaq MRX filing establishes a historical CAT funding fee intended to recover certain past CAT costs via a standardized volume measure called “executed equivalent shares.”
This “historical” fee is separate from the prospective CAT fee for 2026 operating costs (often described as CAT Fee 2026-1). In practice, the two can be additive at the per-execution level.
Event timeline (context)
- May 13, 2026: Nasdaq MRX filed SR-MRX-2026-19 (Historical CAT Assessment 1A).
- May 7, 2026: Nasdaq MRX filed SR-MRX-2026-21 (CAT Fee 2026-1 / prospective fee).
- June 2026: First monthly invoices expected (based on May 2026 activity).
Key numbers and the per-contract math
The fee rates
The filings describe two executed-equivalent-share fees that may both be invoiced on the same monthly schedule:
- Historical CAT Assessment 1A: $0.000002 per executed equivalent share.
- CAT Fee 2026-1 (prospective): $0.000001 per executed equivalent share.
The combined rate is $0.000003 per executed equivalent share if both apply.
What “executed equivalent shares” means
Executed equivalent shares are meant to normalize volume across products so the CAT funding formula can apply consistently:
- NMS stocks: 1 share = 1 executed equivalent share.
- Listed options: 1 contract = 100 executed equivalent shares (based on the typical 100-share multiplier).
- OTC equity securities: 1 share = 0.01 executed equivalent share.
What that implies for options contracts
Using the standard 100-share options multiplier, the approximate fee per options contract per execution is:
- Historical CAT Assessment 1A: $0.000002 * 100 = $0.0002 per contract per execution.
- CAT Fee 2026-1 (prospective): $0.000001 * 100 = $0.0001 per contract per execution.
- Combined: $0.000003 * 100 = $0.0003 per contract per execution.
These are fractions of a cent. The point is not that the fee is “big” on a one-lot trade; it is that the cost can scale with trade count and leg count.
How the fee scales in practice (examples)
Using the combined $0.0003 per-contract-per-execution estimate above:
- 1 contract, 1 execution: about $0.0003.
- 1 contract, round trip (buy then sell): about $0.0006 across both executions.
- 10 contracts, 1 execution: about $0.003.
- 10-lot, 4-leg spread opened in four executions: about $0.012 (and about $0.024 for a round trip).
Two important caveats:
- Your broker may not pass through CAT-related fees 1:1 to customer tickets (it may absorb, bundle, or allocate them differently).
- The above math is a simplified scaling intuition, not a billing statement. In practice, fees are assessed at the executing-broker level and then may be allocated downstream.
Who pays, and how it could reach retail traders
The fees are assessed to “CAT Executing Brokers” (the executing parties identified for the trade). That is an upstream billing point, not necessarily the final economic incidence.
From a trader perspective, there are a few realistic ways CAT-related fees can show up:
- Explicit pass-through line items (per contract or per share) on trade confirmations or in a broker’s fee schedule.
- Bundled regulatory/clearing fees that rise slightly without a distinct “CAT” label.
- Small indirect effects on routing and liquidity-provision economics that can marginally influence spreads or rebates (especially in high-volume, tight-spread products).
None of those are guaranteed for any specific broker. The filings acknowledge that industry fees may be passed through, but each broker can choose how to disclose and allocate costs.
Common misunderstandings
“Historical” does not mean your own historical trades
“Historical” refers to the age of certain CAT costs being recovered (past system costs), not to your personal trading history. The fee is charged on current executions to fund prior costs.
“Commission-free” is not “fee-free”
Even when brokers market $0 commissions, traders can still see regulatory, exchange, and clearing-related line items (or see their impact indirectly through execution costs).
The options multiplier matters
It is easy to glance at $0.000002 per executed equivalent share and assume it is irrelevant. For listed options, the standard calculation treats 1 contract as 100 executed equivalent shares, and the per-execution amount can be paid across many legs and many executions.
What is uncertain (and why wording needs care)
Legal and policy path
CAT funding has faced legal challenges, and the broader funding model has changed over time (including court challenges and subsequent revisions). The Nasdaq MRX filings are part of that evolving process. It is important not to treat any single filing as the final word on how CAT fees will look long term.
How long the historical fee lasts
The historical assessment is intended to collect a specific dollar amount. How long it remains in effect can depend on actual market volumes.
Broker pass-through mechanics
Whether you see a new line item, a bundled change, or nothing visible at all depends on broker policy and disclosure choices.
What to watch in June 2026 (no trade calls)
- Broker fee schedule updates and pricing disclosures in late May and June 2026.
- A new (or adjusted) regulatory fee line item on options confirmations.
- For multi-leg or high-turnover workflows, whether your performance tracking captures small per-trade costs consistently.
Related OptionsTrading.Zone reading (verified URLs)
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 trade recommendation. Options trading involves risk and is not suitable for all investors.
Sources
- SEC Release No. 34-105472 (SR-MRX-2026-19) -
https://www.sec.gov/files/rules/sro/mrx/2026/34-105472.pdf - SEC Release No. 34-105478 (SR-MRX-2026-21) -
https://www.sec.gov/files/rules/sro/mrx/2026/34-105478.pdf - SIFMA letter (Aug 11, 2025) requesting the SEC end CAT fees under the unlawful CAT funding model -
https://www.sifma.org/resources/submissions/letters/request-for-the-commission-to-end-consolidated-audit-trail-cat-fees-imposed-under-the-unlawful-cat-funding-model/ - CAT NMS Plan FAQ: how the funding model works -
https://www.catnmsplan.com/faq/a11
