Individuals new to active trading using margin accounts provided by their Broker/Dealer may soon discover their trading is frozen due to a violation of Pattern Dat Trader rule described below. In brief, if you plan to implement strategies or algos that make frequent trades in a margin account you're going to need to keep a balance of at least $25,000 in the account. You can test your algos in your paper account as long as you set the account balance to more than $25,000. We recommend setting the balance to $1,000,000 so you can feel like a player, and also have lots of room for testing multiple strategies.
This is what FINRA has to say about Pattern Day Trading:
Who Is a Pattern Day Trader?
According to FINRA rules, you’re considered a pattern day trader if you execute four or more "day trades" within five business days—provided that the number of day trades represents more than 6 percent of your total trades in the margin account for that same five business day period.
There are two methods of counting day trades. Please contact your brokerage firm for more details on how they count trades to determine if you’re a pattern day trader.
The rules also require your firm to designate you as a pattern day trader if it knows or has a reasonable basis to believe that you’ll engage in pattern day trading. For example, if the firm provided day-trading training to you before opening your account, it could designate you as a pattern day trader.
In general, once your account has been coded as a pattern day trader account, a firm will continue to regard you as a pattern day trader, even if you don’t day trade for a five-day period, because the firm will have a “reasonable belief” that you’re a pattern day trader based on your prior trading activities. If you change your trading strategy to cease your day trading activities, you can contact your firm to discuss the appropriate coding of your account.
What Are the Requirements for Pattern Day Traders?
First, pattern day traders must maintain minimum equity of $25,000 in their margin account on any day that the customer day trades. This required minimum equity, which can be a combination of cash and eligible securities, must be in your account prior to engaging in any day-trading activities. If the account falls below the $25,000 requirement, the pattern day trader won’t be permitted to day trade until the account is restored to the $25,000 minimum equity level.
In addition, pattern day traders cannot trade in excess of their "day-trading buying power," which is generally up to four times the maintenance margin excess as of the close of business of the prior day. Maintenance margin excess is the amount by which the equity in the margin account exceeds the required margin.
What if I Get a Margin Call?
If a pattern day trader exceeds the day-trading buying power limitation, a firm will issue a day-trading margin call, after which the pattern day trader will then have, at most, five business days to deposit funds to meet the call. Until the margin call is met, the account will be restricted to a day-trading buying power of only two times maintenance margin excess based on the customer's daily total trading commitment. If the day-trading margin call is not met by the deadline, the account will be further restricted to trading only on a cash available basis for 90 days or until the call is met.
Any funds used to meet the day-trading minimum equity requirement or to meet a day-trading margin call must remain in the account for two business days following the close of business on any day when the deposit is required. The use of cross-guarantees to meet any day-trading margin requirements is prohibited.
Why Do I Have to Maintain Minimum Equity of $25,000?
Day trading can be extremely risky—both for the day trader and for the brokerage firm that clears the day trader’s transactions. Even if you end the day with no open positions, the trades you made while day trading most likely have not yet settled. The day trading margin requirements provide firms with a cushion to meet any deficiencies in your account resulting from day trading.
Most margin requirements are calculated based on a customer's securities positions at the end of the trading day. A customer who only day trades doesn’t have a security position at the end of the day upon which a margin calculation would otherwise result in a margin call. Nevertheless, the same customer has generated financial risk throughout the day. These rules address this risk by imposing a margin requirement for day trading calculated based on a trader’s largest open position during the day rather than on open positions at the end of the day.
Firms are free to impose a higher equity requirement than the minimum specified in the rules, and many of them do. These higher minimum requirements are often referred to as "house" requirements