Slightly clarified my comment via a parenthetical. "Non-public" in this context refers to information which would only be available to those with a fiduciary responsibility and/or a confidentiality obligation to the organization.

I was trying to avoid the use of "insider," because people tend to assume that means employees or directors, but that is not the case. Outside organizations who have, as an example, signed an NDA with the organization may learn of material non-public information, and trading on that could constitute insider trading.