Definition
Under FINRA's rule, an account that makes four or more day trades in five business days is flagged as a pattern day trader and has had to hold a minimum of $25,000 in equity. The rule applies to margin accounts. FINRA has proposed changes, so confirm the current requirements with your broker.
Watch out for
The rule does not apply to cash accounts, but those have settlement limits. Check current rules before relying on this summary.