The benchmark S&P/ASX 200 lost 118.6 points to 4980 points.

This represents the benchmark’s first dip below 5000 in more than a week.

Trading opened weak and continued to decline throughout the day, until closing at the lowest point of the session.

The All Ordinaries closed 2.3 % lower at 4998.6, marking a steep drop-off after three months of relatively sustained positive momentum.

The Sydney Morning Herald estimated the share market’s loss on the day at about $A35 billion, the biggest sell-off since last May.

The basic materials sector was among the hardest hit, falling 3.5%, weighed down by the heavyweights.

Rio Tinto and BHP Billiton were down 3% to $67.30 and 3.8% to $37.17, respectively.

It was a busy day for profit results with a large number of miners posting figures.

Iluka Resources and St Barbara dropped 1.4% to $10.20 and 8.6% to $1.22, respectively, after posting reports on heavy year-on-year profit falls.

Despite a profit jump, PanAust fell 6.7% to $2.62.

Alcoa joint venture partner Alumina closed 2.8% lower at $1.21 after posting a $62.1 million loss.

Newcrest Mining closed 3.7% lower, or 81c, to $21.35, while most gold miners sank with the gold price.

Medusa Mining and AngloGold Ashanti each lost 7% to $3.95 and $4.85 respectively.

Whitehaven Coal plunged by 6.1% to $2.94 after the resignation of chief executive Tony Haggarty.