Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

What constitutes illegal insider trading?
It becomes illegal when it is both material and nonpublic information. Material being defined as: Information that you would want and significantly alters the perception of the stock. To your point -- "materiality" is really up to the courts Nonpublic This is a little easier to define, but need to be careful if the information is disclosed selectively -- ie to just a small number of investment analysts -- this may still be nonpublic There is also an exception to this -- Mosaic Theory - This is the research you are referring to where the analyst calls up suppliers, etc and obtains information that is nonmaterial (wouldn't move the price of the security) but using experience and combined with public information creates something that is meaningful and could move the price of the security.  This is perfectly legal.  Material examples: