[Mo_da_Vinci]

Simply, that's an extremely difficult criminal enterprise to pull of especially on an ongoing basis and for what gains? I would only see to do so for spite and active defiance of the law. Is that worth hefty fines, investigations, possible charges and jail time?

A break up usually means many of these people are laid off or move on. Every separate company would have its own books that would either need to be public if they remain public entities or have audited financials that match expenses to revenue and investments. Not an easy thing to hide QTR over QTR. Furthermore, depending on how the companies are broken up, they will be acquired by other companies or PE rather than be stand-alone enterprises. Lastly, whistleblowers.

TL;DR It's not worth it for spite and any significant gains or advantages that are imagined, are probably significant enough to be noticed by the government or some enterprising analyst.