What is the most powerful management consulting company in the world?

I heard about McKinsey, but not sure whether it is top...

The firm which follow the good standars, Has quilified experts will be the one. i hear about some good names like bectel, hill, turner.

It really depends on which field you are asking about .... business, IT, management, networking, oil & gas, finance, ... etc .. etc. You may say Mckensy or Boston group ... etc ... etc ... but you really need to qualify your answer and specify which areas(s) you are asking about 

1. McKinsey by James O. McKinsey
2. BCG Boston Consulting Group by Bruce D. Henderson.
3. Bain & Company
4. Booz by Edwin Booz
5. Deloitte Consulting

Yes, agree with Mr. mohamed Thiab

Bloomberg or  McKinsey?

 Not sure

project management

PMI

PMI and (ISC)2. PMI (www.pmi.org) provides a Project/Program/Portfolio management while (ISC)2 (www.isc2.org) provides an Information Systems Security Management.

This is rather a relative question because I think there is no formal standard of measurement to gauge this. Any company can claim it anytime, anyway, heck!

PMI is the most famous