No one is forcing you to invest in said companies. As an investor it's up to you to do due diligence on the board, conflict of interest disclosures, whether sizeable acquisitions require shareholder approval, etc.
This is on top of blanket legal protections that already exist in case you didn't want to do your own DD, like duty of loyalty, care and fiduciary; SEC disclosures, AD @ the DoJ, FTC, etc.