Switching to Investment Banks or the Big Four from public sector bank

I have a friend who is looking to switch career from an Indian public sector bank. He works as a chief manager on the corporate credit department. Is it possible for him to get into the Big Four (KPMG, Deloitte, E&Y, Pwc)? Or even any investment bank such as JPMC, MS? Both of us have no idea, so any tips will be really helpful.

#finance #banking #career