For several reasons, I think you have a good shot at the schools you listed (or frankly, any other top school you might consider). Typically, b-schools want to see at least a couple of years' work experience under your belt, so you can contribute in the classroom to discussions and projects with real-world answers. While it is unusual for schools to take students without this WE, every year, several do indeed slip in under the radar. The students who do so are outstanding to say the least and posess components of their application such as high GMAT scores (check), leadership experience (check) and a general promise of outstanding performance (check). The most important thing going for your chances, however are the fact that you want to do I-banking. Top firms in this area generally look for sharp, smart, dynamic candidates for their training programs whom they can shape into masters of the universe. Background is not as important as charisma, and raw intelligence. You seem to have a chance of fitting into this category of being recognized as a "boy wonder."
In your application, don't apologize for your age, but try to cast yourself as mature and confident, assured of exactly what your vision is for your career. Maturity will be paramount, as it's your only potential weakness considering your age. Good luck.
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Bryant Michaels
Admissions Consultant