• Brokerage charges for the stocks traded under the day trading segment are very less than Delivery segment.
• High Margin is available for Day trading (eg.If you have Rs.5000 in your account,you will be allowed to do transactions worth multiple times of this value.This ratio varies as per the policy of the Brokerage firms.Some of the brokerage firms even allow upto 10 times margin)
• They do not want to carry their positions overnight as the stock price might be impacted due to some other event and open with a gap up or gap down the next day.

courtesy TradeBeginner.com