whenever major holder (>5%) changes their position by greater than 1% of outstanding they need to file within 3 days.
Here's HHL's last filing for Biota http://asx.com.au/asxpdf/20091028/pdf/31lnrvx0jv50ps.pdf showing 21,178,635 shares for 12.10%.
So HHL now own between 11.11% and 13.09%
Hope that helps.