US companies are shifting their headquarters abroad to protect growing overseas cash piles.
Here is a story about a practice called “inversion” where large corporates move their tax domicile or HQ to lower or nil tax environments. Brilliant info graphics – see link below.
The story is essentially about the global Pharma corporates which have long adopted “Inversion” and 
“Double Irish” but so have the global media corporates and it seems that it is a subject right at the root of the delay in the Omnicom Publicis merger.
For the full FT story click FT.COM