Ann: Change in substantial holding-WOR.AX, page-7

I assume your question was prompted by the notice by Credit Suisse of the change in their substantial holding in WOR.

I am no insider but here is my take on these types of notice.
Some of the transactions will be just picking up pennies on either side of the buy sell spread with algorithmic trading.
Some of the changes in their holding are for borrowing of stock and subsequent short sales by them and other transactions are the converse of that.
Some trades may be actual changes to their longer term "investment" holding in various funds under their control.

If their holding is over the 5% of the stock on issue, which is the threshold for a "substantial" holding and if their aggregate holding then changes by more than 1% up or down, they are required to put in a notice. So they just lump all the transactions together in muck order in one great long list as you see.
If their holding is only ever less than 5%, they are below the substantial holding threshold, in which case they don't have to tell anybody anything about what they are doing, which probably the way they like it best.

Below is a link to the section of the Australian Corporations Act that prescribes the requirements for notices of changes in substantial holdings. Notice that it is predicated on number of votes, so the size of an entity's holding depends on whether it can actually vote the shares. This creates some ambiguity as the right to vote the shares may only change when the shares are registered to the entity, not when the the actual purchase or sale was made.

Most substantial holders seem to work on the basis that the prescribed two day notice period starts when the the purchase or sale was made, but I have encountered a case that was of burning interest to me at the time, where a substantial holder who wanted to sell down their holding in a dying stock, relied on the interpretation that their voting rights did not change until the sales were registered, which at the time gave them another 3 days on top of the 2 day notice period to conduct their selling before they had to tell the market what they had started doing. It took some detective work to figure out that is what they had done, and when I challenged their lawyer/agent about it, they gave that explanation as their interpretation of the law. As usual ASIC were not interested in doing anything to clarify the law. ASIC are about as much use as mammaries on a male bovine.

http://www.austlii.edu.au/au/legis/cth/consol_act/ca2001172/s671b.html

I hope this relieves at least some of your puzzlement.
Cheers