Short Term Trading Week Starting: 16 May, page-340

Find announcements by typing code here: http://www.asx.com.au/asx/statistics/announcements.do

See what milestones are coming cause these will be your volume/price drivers.
Look at AVL today for example, you had free and forrest both talk about upcoming price drivers couple weeks back which are coming to play now.

Top20 can usually be found on company announcements, but if they arent email the company and they usually send one to you.