Big four??

Big4's are the following:

1. Ernst & Young

2. KPMG

3. Deloitte

4. PriceWaterhouseCoopers

They are located in all metro cities and other top cities in India. 

Thank you krishna.

One more question....

Application form for ipce may2012 is available now ?

I didn't get it from the site(icai.org)

Can u help me.

https://icaiexam.icai.org/login.php

Online registration available here.

Do these big 4 companies entertain transfer cases also?

Mostly they wont entertain transfer cases in my opinion. If it is through references, then it may works well. They gives first priority to both groups freshly passed students; and transfer cases comes next.