I found myself reading some things about corporations over on wikipedia, and ran into some stuff about the separation of shareholder and management, and how that could lead to management using the corporation for personal gain rather then the corporation.

http://en.wikipedia.org/wiki/Corporate_law#Balance_of_power

The basic problem is this:

You have a lot of shareholders that invest, but beyond that is very hands off about the daily running of the corporation.

At the same time, you have the day to day managers of the corporation. These have no real investment in the corporation beyond the salary and perks they can get from the position they hold.

End result is that unless the manager pulls of something that makes the shareholder take a personal interest in the daily running, he is basically a lord of the "land".

Then stack on the multinational aspect, and maybe tiered ownership (corp owning corp owning corp), and you may have some asshole running the local show without the powers that be are aware of it (or maybe wants to be aware of it).

Its basically a modern variant of a king appointing a regional governor, and said governor going on a "power trip" that will only stop if the king comes stomping with his army to inspect what all this noise is about.

I don't really have an answer for you, except to say that this is certainly a complicated issue for Sixth World megacorps. In some of the megacorps, power lies in the hands of powerful executives or celebrity shareholders; in others, there is a powerful board that directs the corporation. And yes, in a labyrinthine structure of subsidiaries and tiered ownership, sometimes you'll have as subsidiary that is led by powerful executives that were appointed by the board of the owning corporation, but then take a hands-off approach from there.

As a corporation is a legal entity, the shareholders aren't liable for the company wrongdoings, unless they also sit on the board of chairman and were informed by this way.

For most of the SR megacorporations whose shareholding structure is known (that is, Ares, Aztechnology, Cross, Fuchi, Lusiada, Mitsuhama, Novatech, Saeder-Krupp, Shiawase, Transys Neuronet, Wuxing and Yamatetsu), the shareholders are a lot less numerous than what you'd see nowadays. Most important, nearly all are physical persons (as far as I remember, the only exceptions were Trans-Latvia for Novatech, HKB for Transys and the Malaysian Independent Bank for Wuxing). Renraku is the only possible exception, as little information are available. Several megas has their main shareholder as President and Chief Executive officer.

The amount of money and a power a mere 5% stake in AAA or AA megacorporation represents for a single person means that the only thing they need to take care. Mega shareholders are, for all intents and purposes, the equivalent of a First World parliamentary group leader (that is, because no country as a Parliament with less than a dozen of people seating). They probably have corporate citizenship with the highest possible level of protection (as it wouldn't be not a good idea to let your shareholders subject to laws - and pressures - from their governments). So, I'd expect them to be a more involved than administrators from a pension or hedge fund who make profits over the share value (as opposed to the dividends).

Nonetheless, megacorporation are just too big for everything to be under one centralized control, even with the massive data mining technologies available. There were at least a few cases of small companies fighting against each other unaware they belonged to the same megacorporation (though I'd expect some to be urban legends told among shadowrunners). Corporate Download also tells how Saied Bey, head of S-K Middle East, used to complain how S-K failed to concentrate on profit-making to satisfy Lofwyr personal agenda.

Also, people smart enough to head a division are too rare for megacorp to only recruit them among their employees' families. Like corporate scientists, they should feel a lot less loyal to their megacorporation than lower level executives. As corporate citizens, on the other hand, they must answer to the corporation legal system, which may handle "high treason" just as harshly as countries do.