As with any other style of trading, many different methods of scalping exist. The most well-known scalping technique is using the market's time and sales to determine when and where to make trades. Scalping using the time and sales is sometimes referred to as tape reading because the time and sales used to be displayed on the old-fashioned ticker tape, known as the tape.
The common use of buying on margin (using borrowed funds) amplifies gains and losses, such that substantial losses or gains can occur in a very short period of time. In addition, brokers usually allow bigger margin for day traders. In the United States for example, while the initial margin required to hold a stock position overnight are 50% of the stock's value due to Regulation T, many brokers allow pattern day trader accounts to use levels as low as 25% for intraday purchases. This means a day trader with the legal minimum $25,000 in his account can buy $100,000 (4x leverage) worth of stock during the day, as long as half of those positions are exited before the market close. Because of the high risk of margin use, and of other day trading practices, a day trader will often have to exit a losing position very quickly, in order to prevent a greater, unacceptable loss, or even a disastrous loss, much larger than her original investment, or even larger than her total assets.
There is no special qualification required to become a day trader. Instead day traders are classified based on the frequency of their trading. FINRA and NYSE classify day traders based on whether he or she trades four or more times during a five-day span, provided the number of day trades is more than 6% of the customer's total trading activity during that period or the brokerage/investment firm where he or she has opened an account considers him a day trader. Day traders are subject to capital and margin maintenance requirements.
Spot foreign exchange (exchanges of foreign currencies) brokers - They do not charge any commissions because they make profits from the bid/ask spread quotes. On July 10, 2006, the exchange rate between Euro and United States dollar is 1.2733 at 15:45. The internal (inter-bank dealers) bid/ask price is 1.2732-5/1.2733-5. However the foreign exchange brokers or middlemen will not offer the same competitive prices to their clients. Instead they provide their own version of bid and ask quotes, say 1.2731/1.2734, of which their commissions are already "hidden" in it. More competitive brokers do not charge more than 2 pips spread on a currency where the interbank market has a 1 pip spread, and some offer better than this by quoting prices in fractional pips.