If I shorted then covered the position in the same day, do I still have to pay interest on borrowed stocks? or I pay only if I didn't close my short position before market close & kept it overnight?
No, there should be no interest charge for day trading at all, unless to get your locate you used a third party service.
It's that true with hard to borrow? And some brokers do. I shorted SNAP on a day trade (4 round trips) and did well on the trades until the interest came and reversed all the gains. I paid as though I'd held 4x the position short overnight. I would think as a lender you'd expect the first night's interest for the day trading since you still assume the same risk (of shares not being returned) in absolute terms.
On Lightspeed Trader, yes, as you can recycle locates. RealTick no. Not sure about Sterling Trader Pro. We use Velocity Capital LLC. https://www.lightspeed.com/news/lig...uest-functionality-flagship-trading-platform/
Day trading – the act of buying and selling a financial instrument within the same day, or even multiple times over the course of a day, taking advantage of small price moves – can be a lucrative game. But it can also be a dangerous game for those who are new at it or who don't adhere to a well-thought out method.
Brokers are all over the place on this one. Some charge, some don't. And some charge based on the instrument, which is often an annual interest rate applied to the day. So you need to survey the broker, and ask specifically about the instrument you want to short. Best not to take this one for granted and run into a problem. Good luck.