Hello,
A couple of quick thoughts:
* Don't be so sure that, just because you were grilled in the interview process about your career goals, that's the reason you were rejected. The admissions process isn't as linear as you might think. It may be that the interviewer just focused on that for a certain reason, but, when your interveiw was combined with the rest of your application, ISB just didn't see a fit. We wrote a blog post about this recently:
https://blog.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/07/adm ... -into.html* Even though it's your real reason for wanting to go into finance, "I am fascinated by stocks" doesn't come off as a compelling reason for admissions officers, unfortunately. That too easily leads them to think, "Then it should just remain your hobby." You need to dig deeper into what traits that carer requires, and that you know you have those traits, and here are things in your background that demonstrate those. That matters far more than your level of interest in the subject.
Good luck!
Scott