Investors deserted Australian stocks Wednesday in response to a fall on Wall Street.
The ASX 200 lost 146 points, or 3.3 per cent, to 4,146, reproted dpa.
Bell Potter Securities analyst James Waggett said the most interesting moves were from the giant miners BHP Billiton Ltd and Rio Tinto Ltd, the latter a takeover target for the former.
While BHP lost almost 5 per cent, Rio was up almost 7 per cent, indicating that traders were factoring in a greater likelihood that BHP would succeed with its hostile merger.
"Rumours flew round the market about what may be happening with those merger negotiations - whether or not the EU can come to a decision on the bid sooner, or whether indeed Rio has decided to come to the negotiating table, or even that BHP is looking to raise some cash for a bid," Waggett said.
The negative sentiment carried over to the local currency, with the Australian dollar losing ground to 66 US cents.