Companies are required by law to immediately disclose any information that is considered to have a material effect on the business.

Material information is info that, if disclosed, would have a significant effect on the value or trading price of a company's securities.

The release of material information can be legally delayed (by any appropriate amount of time) in any circumstance whereby the release of the information would be detrimental to the affairs of the company.

If Wyloo did have material information (by virtue of being an insider), such as knowledge of additional PPI data, they would normally be prohibited from sharing this information with BHP (a non-insider) EXCEPT that they are not currently prohibited due to being in the process of discussing a takeover/merger/acquisition/amalgamation/reorganization.  That's from NI 51-201, Part III, 3.1 (3).

Having said all that, I should caution people not to get too excited about a new conspiracy theory arguing that everyone except the public knows about new drill results.  Sure, anything could be happening.  But I don't have any information that leads me to think this is actually the case.  I only brought that up as one of many possible examples that reinforces that the situation [between the three parties to this negotiation] is probably very complicated.  I'm just a random Joe On The Street.  Some of the long-term posters here know me, and know that I don't work in the financial sector.