It's good to see that you're thinking about your future.
I work for a boutique investment bank. The workload is substantial in nearly all areas. As an analyst you will spend a great deal of time at work. I would only recommend a career in investment banking to those who really do enjoy finance. While the pay can be excellent, you will find that it is not that great on a per hour basis in the early part of your career (you could often be working on weekends or late into the evening in some cases). Having said that, I am a firm believer that a couple of years as an investment banking analyst can be a great foundation for a career.
The point that Iâ€™m trying to make is that if your only goal is to get into HBS or Wharton, then you will probably hate investment banking, you wonâ€™t be motivated and your lifestyle will suffer.
Try taking some corporate finance classes at university if possible. This should give you an idea of the basic concepts of finance. I see from the other post that you're studying economics. This is good.
You might want to visit the websites of the various big investment banks. This will give you an idea of the various roles people take at these firms. It can be quite varied and recruiters will expect that you have an understanding of what the firm does in general and what kind of work is done in each area. The nature of work in M&A and Corporate Finance is very different from Investment Management, even though you would need good analytical and writing skills in both.
Here are some links to some top firms:
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