possible take-over, page-17

"only when an official take-over notice is issued to the company, the company needs to make an anouncement"

Not exactly. It used to be that way, but some changes in the 'continuous disclosure' rules now mean that if a company becomes aware of information, which if publicly known would be likely to affect the share price, then they must inform the market. This was tightened up after the classic Fortescue case fiasco.

But its all a bit grey. A few years ago, The Managing Director (Australia) of the NAB sold $3.2m worth of his shares just a few days before the price dropped by more than $4 after an issue announcement. Apparently even as Managing Director he did not know that the bank was about to make a multi-billion dollar issue at a much lower price.

Draw your own conclusions.

I don't sweat the announcement stuff. Sometimes people buy because they see a bit of an increase in volume, which draws in more and so on.