To be safe, you may not disclose any information that is confidential to any company. It is difficult to determine the materiality of particular facts in isolation and you should not attempt to do so. Instead, you should decline any project or inquiry that would involve disclosure of any confidential information.
“Material non-public information” is the legal term for information that can give rise to insider trading liability. Information is “material” if “there is a substantial likelihood that a reasonable investor would consider it important” in deciding whether to buy, sell or hold a security (e.g., a stock or bond). To meet the threshold for materiality, there must exist a “substantial likelihood” that a fact “would have been viewed by the reasonable investor as having significantly altered the ‘total mix’ of information made available.” Information may be deemed material even if it relates to speculative or contingent events.
Information is regarded as “non-public” unless and until it has been broadly disseminated or made widely available to the general public. Means of dissemination could include public filings, coverage by major news organizations, posting on widely-trafficked web sites, publication in research reports and circulation in proxy materials. Even if a public announcement has been made about a particular matter, unpublicized aspects of the matter may remain “non-public” for purposes of the securities laws.