Here is the reg on public companies: http://en.wikipedia.org/wiki/Regulation_Fair_Disclosure http://en.wikipedia.org/wiki/Regulation_Fair_Disclosure For priva

Here is the reg on public companies: http://en.wikipedia.org/wiki/Regulation_Fair_Disclosure http://en.wikipedia.org/wiki/Regulation_Fair_Disclosure For privately held companies there is no equivalent afaik. Especially critical is the time of transition from a privately held company to a public one (IPO). And that's good stuff. The basic idea is that everybody has access to all the information at the same time. The big issue would be if a blog or some other communication wrote 'you should buy this stock' knowing it is a lemon and unloading by someone with a hand in the creation of the blog. That's why it is good practice to fully disclose that you have a position in the companies you write about, because if you do not it may be that afterwards, long after you thought it mattered you could still be hit with a violation depending on what he stock did after you published.