The library
- Mechanisms
- How each type of transaction fraud works, where the money moves, and how attackers adapt
- 44 notes
- Signals
- Device, identity, behavioral, financial and graph signals, and where each one misleads
- 32 notes
Latest
- FBI updates its warning on government and law enforcement impersonation scams
The FBI counted nearly 61,000 complaints and over $1.6 billion lost to government and law enforcement impersonation from January 2025 to July 2026, some using AI video calls.
- Ant International, Mastercard and Visa begin know-your-agent interoperability work
Ant International, Mastercard and Visa began building a shared know-your-agent framework for tracing AI agents to verified operators and users, with no specification, timeline or liability rules yet.
- Scam Center Strike Force seizes a scam services marketplace
US prosecutors seized a Telegram guarantee marketplace serving scam centers and restrained about $52 million in crypto in one day, while OFAC sanctioned the marketplace and two technology suppliers.
- FinCEN scam center alert and what it asks of fraud teams
A close read of FinCEN's scam center alert FIN-2026-Alert005, mapping its victim-payment and laundering red flags to the decision points fraud teams control.
- FINRA files proposal to extend holds to all adult customers
FINRA asked the SEC to approve Rule 2166, a 10-business-day fraud delay for customers of any age, plus longer Rule 2165 senior holds and easier trusted contact collection.
A free, practitioner-built library on how transaction fraud works and how to detect and stop it.
The library covers transaction fraud in retail and in financial services, such as fake receipts submitted to a cashback app or an account takeover that liquidates a brokerage account. It maps the mechanisms, the signals that reveal them, the controls that stop them, and the teams and processes that keep defenses working. It's written by and for the people building those defenses.
Explore the library
| Section | What you'll find |
|---|---|
| News | Recent regulatory changes, enforcement actions, emerging threats and analysis |
| Mechanisms | How each type of transaction fraud works, its transaction footprint, red flags, defenses and emerging variants |
| Signals | The device, identity, behavioral, financial and graph signals that reveal fraud |
| Controls | Preventive, detective and responsive controls, with friction and cost trade-offs |
| Program | Operating models, governance, QA, incident response, metrics and regulation |
| Industries | Brokerage, cashback and coupons, marketplaces, neobanks, payments and retail |
| Case studies | Public incidents and the lessons they teach |
| Resources | Glossary, frameworks, reports, communities and tools |
| Playbooks Members (members) | Detection logic, review and QA criteria, and response runbooks for Three Sigma members |
| Three Sigma | The vetted practitioner community: shared cases, emerging-pattern alerts and problem-solving |
Ways in
- By where the money moves: Payment Rails Map
- By lifecycle stage: Customer Lifecycle Map
- By what stops it: Mechanism to Control Matrix
- By business: Industries Index
Featured
- Retail: Receipt Fraud (Cashback) · Card-Linked Offer Abuse · Referral Abuse · Refund and Return Fraud
- Financial: Account Takeover (ATO) · Payout Redirection · Instant Funding Abuse (Kiting) · Ramp-and-Dump via Account Takeover
- Emerging: Agentic Commerce Fraud · AI Agent Verification (Know Your Agent) · Generative AI and Deepfake Fraud · Real-Time Payment Rail Fraud · Digital Wallet Provisioning Fraud
- Program: Fraud QA Program · SOP Writing Standards · New Product and Promo Launch Review · Threat Intelligence and Horizon Scanning · Exposure Window Modeling
Access
Basics are open to everyone. Operational detail lives in Three Sigma, a free, vetted community where practitioners also share sanitized cases and trade techniques. See Access Model and the Responsible Publication Policy.