In the past, groups of companies have shown a considerable degree of cooperation in trying to influence politics. Usually that takes the form of founding trade organizations which then do the actual lobbying. For instance the RIAA when it comes to lobbying for stricter copyright laws. No assumption here, simply observation
For an example of suppression that has at least some evidence behind it, consider http://en.wikipedia.org/wiki/Patent_encumbrance_of_large_automotive_NiMH_batteries.
The RIAA is a legal organization that acts overtly. It also doesn't consist of a bunch of companies agreeing to intentionally limit their core business activities.