These are referred to as Psy-Ops and are nothing new. This shit has been going on in various guises and mediums since .... forever! What do you think the fucking television and MSM are for?
pretty sure investment firms also employ social media "experts" who create fake users and flood the comment sections of sites like marketwatch and zerohedge with bullshit propaganda. sometimes the fake users will even argue with each other making the whole thing seem more legit. i believe the whole is to create cognitive dissonance amongst readers. to throw the real issue into disarray. http://en.wikipedia.org/wiki/Cognitive_dissonance