Every fee category in the 19b-4 filing dataset has noise in it — individual exchanges acting on their own timelines, their own pricing decisions, their own infrastructure cycles. CAT fees are different. They are the only category where all nine US exchange families file simultaneously, driven not by individual business decisions but by a single shared cost obligation: the Consolidated Audit Trail. And in 2022 and 2023, every one of them stopped filing at the same time — producing a two-year, industry-wide blackout that has no parallel in any other fee category.
No other fee category shows this pattern: industry-wide activity, a complete stop across all participants, then a synchronized restart. The 2022–2023 gap is the defining feature of the CAT fee filing record, and it is not a data artifact — it is confirmed across all nine exchange families simultaneously.
The filing record has three distinct phases. The first phase (2017–2021) is the establishment period, beginning with the original CAT NMS Plan adoption in June 2017 and continuing through annual adjustments as CAT costs were allocated among SROs. The second phase (2022–2023) is the blackout — zero filings across the entire industry. The third phase (2024–present) is the restart, with filing volumes not only returning but exceeding pre-blackout levels, peaking at 72 filings in 2025 and 56 through May 2026 alone.
Cboe leads all exchange families with 91 total CAT fee filings, reflecting its six registered venues (BZX, BYX, EDGX, EDGA, Cboe, C2). Nasdaq follows with 64, NYSE with 53, and MIAX with 46 across its four venues. MEMX (13) and LTSE (10) joined CAT filing activity in 2020, the year after they launched, establishing their cost-sharing obligations for the first time.
From January 1, 2022 through December 31, 2023, not a single US exchange filed a CAT-related fee rule change with the SEC. This is not a gap caused by one exchange family going quiet — it is a simultaneous, complete halt across NYSE, Nasdaq, Cboe, MIAX, BOX, IEX, MEMX, LTSE, and FINRA. In any other fee category, a two-year gap for one exchange would be notable. Here, it happened to all of them at the same time.
This kind of synchronized inaction is only possible in a category where all exchanges share the same external obligation. When that obligation is frozen — whether due to plan amendments, cost formula revisions, or renegotiation of the underlying funding mechanism — no exchange has anything to file, because the source of the fee change is external to every one of them.
The CAT NMS Plan has been through several rounds of significant amendment since it was originally approved in November 2016. The period encompassing 2021–2023 coincided with extensive rulemaking activity around how CAT costs are allocated among SROs and industry members, as the SEC worked to revise the funding model that was originally set out in the plan. During this period, the underlying cost formula that drives exchange CAT fee schedules was in flux, and no exchange had a stable basis on which to file a fee change.
When the new framework stabilized, all exchanges filed at once — and the September 2024 restart was as synchronized as the 2017 launch had been.
The first CAT fee filing after the two-year blackout landed on September 3, 2024. Within three weeks, every exchange family had filed — twelve separate filings on September 3 alone, followed by clusters on September 4, 5, 9, 10, 11, 12, 13, and 25. By September 30, all nine SRO families had resumed their CAT cost-sharing obligations.
September 3: 12 filings — Cboe (6 venues), BOX, IEX, MEMX, MIAX (2 venues), NYSE. The first CAT fee batch since December 2021.
September 4–5: Nasdaq (6 venues), NYSE (4 venues), MIAX (3 venues), FINRA. All Nasdaq venues filing on September 5 completed the first full-industry restart batch.
September 9–12: LTSE, MIAX (4), BOX, IEX, MEMX, Cboe (3), Nasdaq (4). Final stragglers confirming that 100% of SRO families had re-engaged within 10 business days.
September 25: NYSE (5 venues) — the final September 2024 batch, bringing the month's total to approximately 50 filings.
The restart pattern confirms that these are not independent decisions. No exchange "decided" to resume CAT fee filings in September 2024 — they all received the same signal from the CAT NMS Plan's revised cost allocation formula, and all filed within the same short window. The spread from first to last filer (September 3 to September 25) reflects only administrative processing time, not different underlying decisions.
On May 12, 2026, 25 exchange venues filed CAT fee rule changes on the same day — the largest single-day coordinated filing event anywhere in the 19b-4 dataset across all fee categories. The wave continued across the week of May 11–18, ultimately encompassing at least 55 filings from all nine exchange families within eight days.
The May 12 batch included Cboe's six US equity venues (BZX, BYX, EDGX, EDGA, Cboe, C2), NYSE's five venues (NYSE, NYSE Arca, NYSE American, NYSE National, NYSE Texas), MIAX's four venues (MIAX, MIAX Pearl, MIAX Sapphire, MIAX Emerald, plus two additional MIAX Pearl and MIAX Sapphire filings), IEX (twice), and BOX — all on the same calendar day. Nasdaq filed on May 14 and 15, MEMX on May 15, and LTSE and FINRA on May 18, completing the wave.
The appearance of NYSE Texas and Nasdaq Texas in the May 2026 batch is notable. Both are newly registered exchanges that launched in late 2025 and early 2026 respectively. Their inclusion in the May 2026 CAT wave — alongside all legacy SROs — means all registered US exchanges are now simultaneously contributing to CAT cost sharing, including the newest entrants.
The Consolidated Audit Trail (CAT) is the SEC's centralized database for tracking all orders and trades across US equity and options markets. Mandated by SEC Rule 613 (adopted July 2012), CAT requires every broker-dealer and exchange to report order lifecycle data to a central repository operated by CAT, LLC — a subsidiary of FINRA.
Building and operating CAT is expensive. The costs are shared among SROs according to a formula set out in the CAT NMS Plan, which all exchanges and FINRA have adopted as a governing document. When CAT's operating costs change — due to new infrastructure, expanded reporting requirements, or changes in reported trading volumes — the cost allocation formula produces a new set of fee schedules for each SRO. Every SRO receiving a new cost allocation must file a 19b-4 to update its CAT fee schedule.
This is the mechanism behind the synchronization: a single external cost event produces a mandatory filing obligation for every SRO simultaneously. Unlike port fees or colocation fees, which individual exchanges can raise or lower at their own discretion, CAT fees are not discretionary — they are the exchange's share of a shared infrastructure bill.
The synchronization goes deeper than just the timing. The amounts are also externally driven. Two exchanges facing the same CAT cost allocation formula and the same market share denominator will arrive at the same fee adjustment. This is the opposite of every other fee category, where each exchange independently sets its own rates, structures, and competitive pricing. In CAT fees, the exchange is a pass-through, not a price-setter.
This also explains why newer exchanges appear in CAT filings almost immediately after launch. MEMX launched in September 2020 and filed its first CAT fee changes in 2020. LTSE launched in October 2019 and filed its first CAT changes in 2020. 24X National Exchange appears in the May 2026 batch. Each new SRO joins the cost-sharing framework on its first annual cycle, producing its first CAT fee filing as a kind of regulatory debut.
The table below shows raw CAT fee filing counts per exchange group per year. The 2022–2023 columns are empty for every row. The post-restart volumes (2024–2026) are higher than the pre-blackout period for most exchange families, reflecting both the completion of the funding model revision and the expansion of the SRO universe.
| Exchange | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 | 2026* | Total |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Cboe | 18 | 0 | 0 | 16 | 11 | — | — | 17 | 17 | 12 | 91 |
| Nasdaq | 6 | 13 | 0 | 1 | 7 | — | — | 12 | 13 | 12 | 64 |
| NYSE | 18 | 0 | 0 | 5 | 0 | — | — | 10 | 10 | 10 | 53 |
| MIAX | 5 | 0 | 1 | 4 | 0 | — | — | 14 | 12 | 10 | 46 |
| Other / FINRA | 4 | 0 | 1 | 2 | 1 | — | — | 4 | 4 | 5 | 21 |
| IEX | 4 | 0 | 0 | 2 | 1 | — | — | 3 | 4 | 2 | 16 |
| BOX | 4 | 0 | 0 | 2 | 0 | — | — | 3 | 4 | 2 | 15 |
| MEMX | 0 | 0 | 0 | 2 | 1 | — | — | 4 | 4 | 2 | 13 |
| LTSE | 0 | 0 | 0 | 2 | 0 | — | — | 3 | 4 | 1 | 10 |
| Total | 59 | 13 | 2 | 36 | 21 | 0 | 0 | 70 | 72 | 56 | 329 |
* 2026 data through May 25, 2026 (partial year). Dashes (—) indicate zero filings. Source: SEC Federal Register 19b-4 filings database.
Of 329 total CAT fee filings, 15 have been withdrawn — a rate of 4.6%, slightly higher than the overall 19b-4 withdrawal rate of around 3%. Most CAT withdrawals are not reversals of fee decisions — they tend to reflect superseding filings, where an exchange refiled a corrected or updated version of the same fee change and withdrew the original.
Cboe and MIAX account for 5 withdrawals each (roughly 5.5% of their respective CAT filings). MEMX (2 withdrawals, 15.4% of its 13 CAT filings) and LTSE (1 withdrawal) show higher rates, consistent with the pattern of newer entrants experiencing more administrative amendments as they establish their CAT fee frameworks for the first time. NYSE and Nasdaq have zero CAT fee withdrawals — reflecting their longer institutional experience with the filing process and their more established relationships with the SEC's Division of Trading and Markets.
Source: All 19b-4 filings published in the Federal Register from January 1, 2017 through May 25, 2026, for exchanges in the NYSE, Nasdaq, Cboe, MIAX, BOX, IEX, MEMX, LTSE, and Other (including FINRA) families. Data extracted via the Federal Register API and stored in a local SQLite database of 10,610 filings.
Classification: Filings are classified as FEE_CAT when their title contains keywords related to CAT, Consolidated Audit Trail, or Rule 613 fee obligations. This is a title-based classification; filing bodies are not read during classification. A small number of CAT-related filings that use atypical title language may be excluded.
Filing attribution: Each exchange venue is counted separately. When Cboe files across all 6 of its venues on the same date, that counts as 6 filings. This matches the regulatory reality — each is a distinct legal filing with the SEC that must be separately noticed, commented upon, and potentially suspended.
The blackout confirmation: The 2022–2023 zero-filing result was verified by directly querying the database for all filings with filing dates in those years and category = 'FEE_CAT'. The result is zero. The same query across all other fee categories produces non-zero results for 2022 and 2023, confirming the blackout is category-specific.