Aust shares open lower The Australian share market has opened lower due to concerns about the US debt ceiling, weak economic data from Japan and political turmoil in Italy. The biggest worry for investors is the debt ceiling negotiations in the US, where the government is headed for a shutdown that will close services deemed non-essential. A political crisis is also engulfing Italy's fragile coalition government, while the latest industrial production numbers from Japan proved weaker than expected. The release of Chinese manufacturing data later on Monday will be closely watched by investors. IG market strategist Evan Lucas said caution was dominating early trade, and may remain for most of the week. "The risk tone has not been particularly positive with a lot of flows to more safe haven assets," he said. The chances are we will see some of these defensive names outperforming the market today. Defensive stocks, such as the supermarket chains and health care companies, were lower in early trade, but had posted smaller falls than other sectors. In resources, mining giant BHP Billiton had dropped 45 cents to $35.91, Rio Tinto was $1.04 lower at $62.25 and Fortescue Metals had shed eight cents to $4.86. Energy stocks were also significantly lower. Among the banks, ANZ was down 44 cents at $31.08, Commonwealth had given up 78 cents to $72.38, Westpac had dropped 37 cents to $32.93 and National Australia Bank was 38 cents lower at $34.73. At 1035 AEST on Monday, the benchmark S&P/ASX200 index had dropped 54.7 points, or 1.03 per cent, to 5,252.4. The broader All Ordinaries index had lost 52.9 points, or 1.0 per cent, to 5,249.4. The December share price index futures contract was 58 points lower at 5,251, with 7,531 contracts traded. National turnover was 317.4 million securities worth $431.8 million.