Consolidated audit trail
CATAlso called CAT NMS Plan
The consolidated audit trail (CAT) is a central US database that records the full life of every order in national market system equities and listed options, from receipt through routing, modification, cancellation and execution. Broker-dealers and exchanges report to it so regulators can reconstruct market activity across venues.
How it works
Broker-dealers send order events to CAT through automated feeds, typically by 8am Eastern on the trading day after the event. Each record carries timestamps, order details and identifiers that link an order as it moves between firms and venues. Firms must correct errors flagged by the system within set deadlines, so data quality checks run daily.
CAT replaced a patchwork of exchange audit trails that could not follow an order across markets. Regulators use it to investigate manipulation, insider dealing and market events such as flash crashes. Its scale, cost and the collection of customer data have drawn sustained criticism, and the SEC opened a broad review of its future in 2026.
The rules
Required the self-regulatory organisations to submit a national market system plan to build and run a consolidated audit trail.
National securities exchanges and FINRASEC-approved plan setting out what order data must be reported to CAT, by whom and when.
Exchanges, FINRA and their broker-dealer membersExempts firms from reporting names, addresses and years of birth of natural-person customers to CAT.
CAT reportersCommon questions
Who has to report to CAT?
National securities exchanges, FINRA and broker-dealers that handle orders in NMS stocks, listed options or OTC equity securities report to CAT. Firms can use third-party reporting agents, but the reporting firm remains responsible for the accuracy of what is submitted.
What data does CAT collect?
CAT collects order events such as receipt, routing, modification, cancellation and execution, with timestamps and identifiers that link them. It also holds customer and account reference data. Since a 2025 SEC exemption, names, addresses and years of birth of individual customers are no longer reported.
How does CAT differ from MiFIR transaction reporting?
MiFIR transaction reporting in the EU and UK captures executed transactions sent to national regulators. CAT covers the full order lifecycle, including orders that are never filled, and sends it to a single central repository for US regulators.
What is the SEC's 2026 review of CAT?
In April 2026 the SEC published a concept release on CAT's future. It asked for views on funding and governance, scope and technical design, and cybersecurity and data privacy. The comment period closed in June 2026.
