Hello , I am a systematic futures trader from France interested in stock trading. I've never traded stocks and I would like to know how credit interest rate works. How can you incorporate credit interest rates in backtests? For TS, it's 1.5 %, but how do you calculate what you will have to pay based on the initial position and the margin you have? Does it apply to short positions with no leverage since you borrow shares? I'm a total newbie to it.. PLease help me.