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 in this sense is the practice of purchasing a security for one's own account shortly before recommending that security for long-term investment and then immediately selling the security at a profit upon the rise in the market price following the recommendation. The Supreme Court of the United States has ruled that scalping by an investment adviser operates as a fraud or deceit upon any client or prospective client and is a violation of the Investment Advisers Act of 1940. The prohibition on scalping has been applied against persons who are not registered investment advisers, and it has been ruled that scalping is also a violation of Rule 10b-5 under the Securities Exchange Act of 1934 if the scalper has a relationship of trust and confidence with the persons to whom the recommendation is made. The Securities and Exchange Commission has stated that it is committed to stamping out scalping schemes.
Assess how much capital you're willing to risk on each trade. Many successful day traders risk less than 1% to 2% of their account per trade. If you have a $40,000 trading account and are willing to risk 0.5% of your capital on each trade, your maximum loss per trade is $200 (0.005 x $40,000). Set aside a surplus amount of funds you can trade with and you're prepared to lose. Remember, it may or may not happen.