It is estimated that more than 75% of stock trades in United States are generated by algorithmic trading or high-frequency trading. The increased use of algorithms and quantitative techniques has led to more competition and smaller profits. Algorithmic trading is used by banks and hedge funds as well as retail traders. Retail traders can choose to buy a commercially available Automated trading systems or to develop their own automatic trading software.
Sincere interviewed professional day trader John Kurisko, Sincere states, Kurisko believes that some of the reversals can be blamed on traders using high-speed computers with black-box algorithms scalping for pennies. “That’s one of the reasons many traders get frustrated with the market. The timing is not like it used to be, and many of the old rules don’t work like before.” 
A trader can measure their performance as a percentage of the trading channel width. The perfect trade would be buying at the bottom channel line and selling at the top channel line, which would be a 100% performance. If a trader captured one-half of the channel, it would be a 50% performance. The goal is to continually increase the performance percentage of the average winning trade.
Some of the common mistakes that scalpers make are poor execution, poor strategy, not taking stop-losses, over-leveraging, late entries, late exits and overtrading. Scalping generates heavy commissions due to the high number of transactions. A per-share commission pricing structure is beneficial to scalpers, especially for those who tend to scale smaller pieces in and out of positions.
Scalping can appear easy because a scalper might make an entire day's profit within a few minutes. However, in reality, scalping can be quite challenging because there is very little room for error. If you do decide to try scalping, make sure that you do so by using a trading simulator, until you are consistently profitable and no longer make any beginning mistakes, such as not exiting your trades when they move against you.
Article copyright 2011 by Alex Elder. Reprinted and adapted from Come Into My Trading Room with permission from John Wiley & Sons, Inc. The statements and opinions expressed in this article are those of the author. Fidelity Investments® cannot guarantee the accuracy or completeness of any statements or data. This reprint and the materials delivered with it should not be construed as an offer to sell or a solicitation of an offer to buy shares of any funds mentioned in this reprint.
This combination of factors has made day trading in stocks and stock derivatives (such as ETFs) possible. The low commission rates allow an individual or small firm to make a large number of trades during a single day. The liquidity and small spreads provided by ECNs allow an individual to make near-instantaneous trades and to get favorable pricing.
Scalping can be very profitable for traders who decide to use it as a primary strategy, or even those who use it to supplement other types of trading. Adhering to the strict exit strategy is the key to making small profits compound into large gains. The brief amount of market exposure and the frequency of small moves are key attributes that are the reasons why this strategy is popular among many types of traders.
Another risk of swing trading is that sudden reversals can create losing positions. Because you are not trading all throughout the day, it can be easy to be caught off guard if price trends do not play out as planned. To decrease the risk of this happening, we recommend issuing stop orders with every new position. Stop orders can help you “lock-in” your gains and can also help you cut your losses.
Day trading requires more money than just a deposit, though. Get setup with a good computer, one or two monitors, a trading platform and data feeds. With many brokers the data feeds for various markets cost money, so pick a market and stick with it. There is no reason to pay for data feeds you won't be using. Also, a consistent income isn't likely during the first six months to a year, so save up for living expenses if attempting to day trade as a primary income stream.
ECN/Level 2 quotes: ECNs, or electronic communication networks, are computer-based systems that display the best available bid and ask quotes from multiple market participants and then automatically match and execute orders. Level 2 is a subscription-based service that provides real-time access to the Nasdaq order book composed of price quotes from market makers registering every Nasdaq-listed and OTC Bulletin Board security. Together, they can give you a sense of orders being executed in real time.