NO idea really, profit and broker upgrades, record work in hand, takeover? consolidation? Here's a couple of relevent articles
http://www.aireview.com/index.php?act=view&catid=2&id=2531
http://www.theage.com.au/news/Business/Macquarie-wanted-to-buy-Hochtief-report/2005/08/24/1124562887906.html
http://www.newratings.com/analyst_news/article_974987.html