most business analyst responsibilities are more along the lines of system project planning and implementation. from my experience, business analysts gather requirements from the business side, write them up and deliver them to the systems/technical side for new systems, system upgrades, or other technical projects. they also assist in testing and implementation. I think of it as being a translator between the business and the IT groups. usually you need both the business skills and the technical skills, but you don't necessarily make any investment decisions per se. I dont know what the job responsibilities are for a BA at mckinsey. If you're doing M&A and due diligence, i would imagine that would count. BA is just a title. just like that thread in the general forum about a trader vs. execution trader, there is a lot of flexibility in any title.