a lot of companies engage in incomplete and preliminary...

a lot of companies engage in incomplete and preliminary discussions with potential suitors that never get off the ground or amount to anything they don't necessarily come out and disclose them in an ASX announcement.

Listing Rule 3.1A.1 mentions information concerning incomplete proposal or negotiation. these things can remain commercial in confidence until such time as for example what happen here where it was leaked by the Australian at which time as the confidentiality is broken must be disclosed.

Listing Rule 3.1A.1 - the categories of information excluded
The first requirement for Listing Rule 3.1A to apply is that the information must fall within one of the categories
mentioned below:
 it would be a breach of a law to disclose the information;
 the information concerns an incomplete proposal or negotiation;
 the information comprises matters of supposition or is insufficiently definite to warrant disclosure;
 the information is generated for the internal management purposes of the entity; or
 the information is a trade secret.

An entity which is relying on Listing Rule 3.1A not to disclose information about a market sensitive transaction it is
negotiating should as a matter of course be monitoring, either itself or through its advisers:
 the market price of its securities and of the securities of any other listed entity involved in the transaction;
 major national and local newspapers;

PS I am not forming a view on whether (or not ) PBH should have (or were required to) disclose this as part of the ASX query. Im just merly stating that but for the SP tanking last week and the ASX query. in the ordinary course of business a company does not have to immediately inform its shareholders regarding incomplete proposals.