At 10.15am (AEST), the benchmark S&P/ASX200 index was down 40.6 points, or 0.86 per cent, at 4672.7, while the broader All Ordinaries fell 38.2 points, or 0.81 per cent, to 4676.6.
RBS Morgans private client adviser Craig Walker said resources and financials were the main contributors to a weaker market in early trade.
"The market at the moment is down around one per cent,'' Mr Walker said.
"The biggest contributors have been in the large cap stocks, such as BHP, most of the major banks, QBE Insurance, Wesfarmers and Newcrest.
"There are not too many parts of the market that are looking overly positive today.''
Resources headed up the losses.
BHP Billiton was down 1.49 per cent to $36.99, and Rio Tinto fell 1.47 per cent to $59.10.
Major gold stocks were down.
Newcrest Mining shed 80 cents to $32.60, Lihir Gold lost 5 cents to $2.90, and Newmont was steady at $4.96.
The spot price of gold in Sydney was $US994.92 per fine ounce, up 25 US cents on Friday's closing price of $US994.67.
The big four banks were weaker.
ANZ lost 2 cents to $23.77, NAB fell 1.05 per cent to $30.10, Commonwealth Bank shed 1.44 per cent to $50.56 and Westpac reversed 1.49 per cent to $25.78.
Making news, department store operator Myer will have a market value of between $2.28 billion and $2.77 billion when it floats on the stock exchange in November.
Upmarket department store David Jones gained 1.25 per cent to $5.68 at 10.30am.
Amongst other retail stocks, Coles owner Wesfarmers fell 1.43 per cent to $26.28, and Woolworths slid 16 cents to $28.98.
On Friday, Wall Street shares fell for a third consecutive day as disappointing economic data prompted investors to retrench ahead of the weekend.
The Dow Jones Industrial Average slipped 42.25 points, or 0.44 per cent, to close at 9665.19 in a choppy session that saw modest swings in both directions.
The technology-heavy Nasdaq composite dropped 16.69 points, or 0.79 per cent, to 2090.92 and the Standard & Poor's 500 index shed 6.40 points, 0.61 per cent, to 1044.38.
On the Sydney Futures Exchange, the December share price index contract declined 45 points to 4680, on a volume of 6086 contracts.
Stocks tumble amid investors’ worriesResources push shares lower at noon
