The XJO is presently down 30 points (-0.6%), at 4380.
Most sectors are weaker, with materials, energy and consumer discretionary stocks the weakest links.
In company news, NWH has dropped 4.5% after BHP announced it will axe part of its $120 million contract at Port Headland.
Elsewhere, Nufarm is down 1.7% despite reporting an FY12 net profit after tax of $72.6 million a massive swing from net loss of $49.9 million it posted in FY11.
Around the region, Asian markets are all weaker; the Shanghai Composite is down 0.9%, whilst the Nikkei is down 0.7%.