Buying on margin can greatly increase your gains or losses. Brokerages usually allow a bigger margin percentage for a day trading account but reduce the amount of margin available for positions held overnight. Normally a day trading account must have a minimum of $25,000 and can buy on margin at a rate of 4 to 1 giving you $100,000 in buying power, which is called day trader buying power. That number drops to 2 to 1 for positions held overnight, which can be called overnight margin buying power. That means that if you have 100% of your margin being used during the day, you must exit at least half of your positions before the close of the trading day.
Some of these approaches require short selling stocks; the trader borrows stock from his broker and sells the borrowed stock, hoping that the price will fall and he will be able to purchase the shares at a lower price, thus keeping the difference as their profit. There are several technical problems with short sales - the broker may not have shares to lend in a specific issue, the broker can call for the return of its shares at any time, and some restrictions are imposed in America by the U.S. Securities and Exchange Commission on short-selling (see uptick rule for details). Some of these restrictions (in particular the uptick rule) don't apply to trades of stocks that are actually shares of an exchange-traded fund (ETF).
Day trading poses a number of hurdles. Mainly, each trading day is slightly different. Traders need a method that works in nearly all market conditions. That doesn't mean a day trader will win every day. On the contrary, even with a great method, there still may be several losing days a month. Winning every trade or every day isn't important, it is winning over the course of each week and month that matters.
By holding overnight, the swing trader incurs the unpredictability of overnight risk such as gaps up or down against the position. By taking on the overnight risk, swing trades are usually done with a smaller position size compared to day trading (assuming the two traders have similarly sized accounts). Day traders typically utilize larger position sizes and may use day trading margin of 25%.

Smaller moves, easier to obtain - A change in price results from imbalance of buying and selling powers. Most of the time within a day, prices stay stable, moving within a small range. This means neither buying nor selling power control the situation. There are only a few times which price moves towards one direction, i.e. either buying or selling power controls the situation. It requires bigger imbalances for bigger price changes. It is what scalpers look for - capturing smaller moves which happen most of the time, as opposed to larger ones.
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In addition to knowledge of basic trading procedures, day traders need to keep up on the latest stock market news and events that affect stocks—the Fed's interest rate plans, the economic outlook, etc. So do your homework. Make a wish list of stocks you'd like to trade and keep yourself informed about the selected companies and general markets. Scan business news and visit reliable financial websites.