Since Raj Rajaratnam has been the biggest IT case recently, I looked back at some articles on his case to see if it stated how Preet Bharara or the prosecutors determined "material" or "non-public" info that is traded on.
Here's a 5/12/11 article after he was convicted and a quote from it:
Prosecutors dismantled Mr. Rajaratnam’s defense by acknowledging that Galleon performed legitimate research. But at the same time, they argued, the firm routinely violated securities laws.
In the words of a former Galleon portfolio manager who testified during the trial, the firm did its homework — but also cheated on the test. Mr. Rajaratnam sought out information that was confidential, beyond the reach of research, and illegally traded on it.
****So from the his case, IT is based on ""Confidential and beyond the reach of research.""****