What Is a Suspicious Activity Report (SAR)?

By Kristi Waterworth – Updated Oct 19, 2025 at 9:03 PM

Key Points

SARs help track financial crimes like money laundering at banks, impacting investor confidence.
Banks must file SARs for unusual transactions; failure to do so results in severe penalties.
Investors should communicate openly with banks about large transactions to avoid triggering SARs.

Suspicious activity reports (SAR) have been a tool for banks to report activity that wasn't necessarily blatantly illegal but certainly seemed odd since the Bank Secrecy Act of 1970. Although many things that trigger a SAR turn out to be run-of-the-mill transactions, the Financial Crimes Enforcement Network (FinCEN) uses them to document and track criminal activity. Read on to learn more.

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People shaking hands over a desk in a bank. — Image source: Getty Images.

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About the Author

Kristi Waterworth has been a contributing real estate and financial expert at The Motley Fool, covering real estate, investing, and personal finance topics, since 2020. Kristi has been interviewed by various TV media outlets and podcasts for her real estate investing expertise – from residential real estate to digital real estate and everything in between. Kristi’s journalist career spans over 25 years, and she has written about real estate investing, homeownership, and home construction specifically for the last decade. She was also previously a licensed Realtor and general building contractor before the Great Recession and housing market collapse. She holds a bachelor’s degree in American history from Columbia College in Missouri.

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