What is “3 Roundtrip Control”?

It’s a rule of FINRA and SEC rule, if the equity on your account is less than $25000, you are not allowed to daytrade, meaning you can’t have more than 3 round trips or engage in pattern day trading in 5 days. It only applies to accounts held at US Broker dealers. It does not apply to non-US registered firms. One roundtrip means to buy and sell the same stock. A pattern daytrading is the buy and sell of the same stock on the same day.