Day traders are basically the market markers. They create liquidity in the market by frequently buying and selling stocks throughout the day in the hope that the price of the stocks will fluctuate so that they can make profits with that fluctuation. Most traders buy stock and want the prices of a stock to rise so that they can make a profit, but some have alternate arrangements by following short selling of stocks to profit when their prices fall and purchase again at lower prices to make profit.
Day traders hold stocks anywhere from a few seconds to a few hours but at the end of the day they will always setoff their position before the stock exchange's normal closing time. They specifically control their activity to avoid risks arising from events happening after closing hours of the market. If they carry over the stock for next day they would be at risk of losing out on their gains due to negative news inflows on stocks, sectors or the markets. Therefore, the objective of the day trader is to benefit from frequent purchase and sale activities of any underlying stock in a particular day.
Day traders are further categorized into two different groups: (a) scalpers, and (b) momentum traders.
Scalpers: This group of day traders trading is like playing hot potatoes. Their activities are limited to the rapid and repeated buying and selling of a large volume of shares during a very short period of time, anywhere from a few seconds or a few minutes at a time. The group trades on those shares that have high liquidity and momentum in prices. New listing of shares is one kind of example where Scalpers are active. Their objective is to earn a small per share profit on each transaction at a minimum risk.
Momentum Traders: These types of day traders identify and trade stocks that are moving in a particular range during the day. Their objective is to buy stocks at the bottom and sell them at the top or vice-versa.