At one stage the market was up more than 1% before a sharp reversal saw it finish in negative territory.
Financials were the biggest drag on the market, with ANZ and Westpac shedding more than 1% each.
The two mining giants were mixed, with Rio Tinto inching up 0.1% and BHP losing 1.2%.
Amcor was among the bright spots (+2.6%) following its plans for a share buyback, whilst James Hardie jumped 4.8% after receiving a favourable court ruling.
Among the energy stocks, Caltex finished flat despite reporting a 24% fall in first-half profit.
The ASX 200 fell 20 points (-0.5%), closing at 4082.