When a client opens an account with a broker, the client can choose a “margin account” or a “cash account.” A margin is a loan that brokers provide to stock traders. As with every loan, margin bears interest unless the stock trader uses it only during the course of the trading day, in which case no interest is paid.

Margin trading is highly speculative. In light of the dangers inherent in using margin, day-trading rules prohibit U.S.-regulated brokers from providing margin greater than 4:1 (i.e., a multiple of four times your money) for any single trading day, or greater than 2:1 for stocks held more than one day. For example, if you deposited $30,000 with a U.S.-regulated broker, you would be able to buy stocks valued at $120,000 intraday. If you wanted to hold stocks overnight, you would need to be satisfied with a 2:1 margin, and you would be charged interest.

These rules do not apply to brokers and investment firms that are headquartered and regulated outside of the United States. For example, non-U.S. residents can open an account that offers margin up to 20:1.

The advantage of margin is that you don’t need to make a much larger deposit in order to trade with higher sums. The disadvantages of margin are the interest it bears beyond one day’s trading and the risk of losing much more money than you might have lost if trading without the margin.

For Disciplined Day Traders, Trading on Margin is Worthwhile

In our opinion, it is worthwhile to use the intraday margin during one trading day, because you will pay no interest. If you are disciplined and operate according to the rules of day trading, it also is worth using margin beyond one day of stock trading, despite the interest charged, because the “swing trading” method that requires holding stocks for several days is based on aggressive profit goals with anticipated gains of several percent.

As a beginner day trader, you should start with the basics learn to make do with a 4:1 margin, even if you could find a way to qualify for a higher margin. A too-high margin may spin out of control in risky situations when you feel you absolutely “must have” a certain stock. That’s precisely when it’s best to take a deep breath and minimize the risk. A reasonable margin prevents mishaps of this kind. In short, be satisfied with a little less and you will save a great deal.

Trading on Margin Benefits Both Brokers and Day Traders

Brokers are at risk and do not share in the profits you can make from margin, so why would they bother to provide you with margin? There are two main reasons. The first is the fact that they profit from charging interest when you buy on margin and use the funds to hold stock for more than a single trading day. The second reason is that the greater the sum of money accessible to you, the more probable it is that you will execute more transactions with greater volume. Why would you be happy buying just 200 shares if you could profit more from buying 800? In short, margin benefits both sides: the stock trader can put in just one-half or one-quarter of the amount needed and enhance his or her potential on each trade by double or quadruple, while the brokers benefit from the greater volume of activity by earning more commissions.