Which type of listing information must not be disclosed?

The correct answer focuses on the confidentiality of a client's financial status. In real estate transactions, a salesperson has a fiduciary duty to protect sensitive information about their clients. This includes not disclosing anything that could compromise the client’s position in negotiations, such as their financial situation.

In contrast, stigmatized property information, while it may raise ethical considerations, is information that must be disclosed in certain circumstances if it affects the property's desirability. Material facts about the property, such as its condition or legal issues, are also required to be disclosed to ensure that all parties make informed decisions. Known hidden defects are critical as they directly impact the safety, usability, or value of the property, and a seller must disclose these to potential buyers. Thus, the protection of a client’s financial status is paramount and is the correct aspect of listing information that must remain confidential.