Consolidated Audit Trail: Tracking Every US Order

Key Takeaways

• CAT records every order, cancellation, modification, and execution in US equities and options.
• It was built under SEC Rule 613 and replaced FINRA's older OATS in 2021.
• Investors may assume small firms are exempt, but CAT has no size-based carve-outs.
• A single market-wide trail lets regulators reconstruct events and detect manipulation faster.

What It Is

The Consolidated Audit Trail, or CAT, is a comprehensive database that captures the full lifecycle of orders across US securities markets. It was created under SEC Rule 613, which required FINRA and the national securities exchanges to jointly build a single audit trail.

CAT collects and accurately identifies every order, cancellation, modification, and trade execution for all exchange-listed equities and options across all US markets. It replaced the patchwork of separate systems, including FINRA's OATS, that previously covered different slices of the market.

The Intuition

Before CAT, no single system saw the whole market. FINRA had OATS for member equity orders, exchanges ran their own audit systems, and reconstructing a cross-market event meant stitching together data with mismatched formats and timestamps. That made investigations slow.

CAT exists to give regulators one consistent view. By requiring every participant to report order events to a central trail in a uniform format, it lets regulators trace an order from origination through every modification, route, and fill, no matter how many venues it touched. A faster, complete reconstruction means quicker detection of manipulation and a clearer picture during market disruptions.

How the Consolidated Audit Trail CAT Works

Each order event is reported to CAT with a precise timestamp. The events cover the end-to-end lifecycle of a trade: quotes, the original receipt or origination of an order, modifications, cancellations, routing, receipt of a routed order, executions in whole or in part, and ultimately order allocations.

The scope is broad. FINRA reminds all members, regardless of size, that receive or originate orders in NMS stocks, OTC equity securities, or listed options that they must report to CAT. There are no exclusions or exemptions for type of firm or type of trading activity, and proprietary and market-making activity is covered. Even firms that meet the definition of a small broker-dealer must comply.

Accuracy depends on the same disciplines that governed OATS: clock synchronization, consistent timestamps, reliable connectivity and data transmission, recordkeeping, and standards for the timeliness, accuracy, and completeness of data. Introducing firms cannot simply assume a clearing firm reports on their behalf; they need a signed agreement and supervisory systems to confirm the data is timely, accurate, and complete.

FINRA retired OATS once CAT met the accuracy and reliability standards approved by the SEC, completing the transition in 2021.

Worked Example

Suppose a stock experiences a sudden, sharp price drop in seconds, and regulators want to know whether manipulation or a simple error caused it. The order that triggered the move passed through several venues.

With CAT, regulators query the central trail for that window. They see the originating order reported by one firm, its routing to a first venue, a partial fill, rerouting to a second venue, a cancellation of the remainder, and the resulting executions, all stamped with synchronized times. Because every participant reports to the same trail, the full sequence assembles in one place.

Under the old fragmented systems, this would have meant requesting separate records from each firm and exchange, then reconciling formats and clocks. CAT compresses that into a single query against one consistent dataset. The speed of reconstruction is the core benefit.

Common Mistakes

1. Assuming small firms are exempt. CAT has no size-based exemptions. Every member that receives or originates covered orders must report.

2. Believing CAT is public market data. CAT is a regulatory database, not a market data feed. The public does not access raw CAT data.

3. Relying on a clearing firm without an agreement. Introducing firms remain responsible for their CAT data. A signed agreement and supervision are required to delegate reporting.

4. Underestimating clock synchronization. Synchronized, precise timestamps are central to CAT. Misaligned clocks produce an unreliable trail and compliance problems.

5. Treating CAT and OATS as the same scope. CAT covers equities and options across all participants. OATS was narrower, limited to FINRA members and equities, and is retired.

Frequently Asked Questions

What is the consolidated audit trail CAT in simple terms? CAT is a database that records every order, cancellation, change, and trade in US-listed stocks and options across all markets. Regulators use it to reconstruct trading and spot misconduct.

How does the consolidated audit trail affect investment decisions? CAT does not affect individual decisions directly. Its purpose is market integrity, helping regulators detect manipulation and reconstruct disruptions that could harm all investors.

What is a real-world example of CAT in use? After a sudden price drop, regulators query CAT to trace the triggering order through every venue it touched, assembling the full sequence from one consistent dataset.

How can firms comply with the consolidated audit trail effectively? Synchronize clocks, apply consistent timestamps, and confirm reporting arrangements in writing. Introducing firms should not assume a clearing firm reports on their behalf without an agreement.

How is CAT different from OATS? CAT covers equities and options across all US market participants with no size exemptions. OATS was a narrower FINRA system limited to members and equities, and it was retired in 2021.

Sources

1. SEC. "Rule 613 (Consolidated Audit Trail)." https://www.sec.gov/about/divisions-offices/division-trading-markets/rule-613-consolidated-audit-trail
2. FINRA. "Consolidated Audit Trail (CAT)." https://www.finra.org/rules-guidance/key-topics/consolidated-audit-trail-cat
3. CAT NMS Plan. "Official Site." https://www.catnmsplan.com/
4. FINRA. "Regulatory Notice 20-31." https://www.finra.org/rules-guidance/notices/20-31

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.