Corporations are ubiquitous throughout the Twin Spirals. They operate in Hyperspace the same as they do in the real world: quarterly earnings, competitive advantage and stock prices are still a concern, just on a larger scale. Corporations get away with whatever their local or stellar government will let them, or failing that, whatever they can sneak by with no one noticing.
Some corporations are so large as to be stellar nations in their own right. In fact, the most powerful firms are completely independent and have dozens of worlds under their control, whose governments are usually corporate oligarchies (though never officially labeled as such).