Does day-trading count as work experience?

Sorry mere bachhe.. it won't be counted as work experience. All Indian b-schools consider only full-time, paid work as valid work-experience. Contract jobs, internships, unpaid work, part-time work and freelance work are not considered as valid work experience for pre-interview selection process by almost any b-school now. You can mention it in your form for sure (in various b-school applications) and use it to drive interview conversations. It will be looked at as valuable extra-curricular activity or freelance work but beyond that, it won't earn you any marks or score directly. Having said that, be assured that the interviewer will be supremely happy to have in-depth conversations with you on trading and client management, and this will increase your chances of converting an interview drastically. But it won't help you reach the interview room.