Stocks slip in anticipation of Fed stimulus news Australian shares have slipped from five-year highs as uncertainty about the US Federal's stimulus direction hits the big miners. The policy-setting Federal Open Market Committee began meeting on Tuesday and many investors expect Chairman Ben Bernanke to announce a reduction of bond purchases by $10 billion a month to $75 billion, while keeping interest rates close to zero. Invast Securities chief markets analyst Peter Esho said BHP Billiton and Rio Tinto were particularly susceptible ahead of the conclusion at 4am Thursday AEST of the US central bank's two-day meeting. ""With the Federal Reserve meeting ... what we're seeing, not just in Australia but across the region, is some caution amongst traders, just waiting for some clarity,"" he said. ""The energy and materials (sectors), definitely, are playing a part in weighing down the market. ""We are very much a mining and resource proxy for global markets, and what comes out of the Fed is going to be very sensitive to commodity prices."" By midday BHP had dropped three cents to $36.11, Rio had lost 59 cents to $62.17 and Fortescue Metals Group had shed six cents to $4.56. Another miner, Santos, slumped 14 cents to $14.86 after NSW environmentalists demanded information on waste water from eight new coal seam gas wells in the NSW Pilliga forest. But three of Australia's big four banks were firmer after Reserve Bank of Australia assistant governor Malcolm Edey said talk of a local housing bubble was ""unrealistically alarmist"." National Australia Bank had gained nine cents to $34.77, Commonwealth Bank was up 27 cents to $73.87 and Westpac up 16 cents to $32.63. ""The banks have a bit of a cushion,"" Mr Esho said. ANZ, however, had dropped 13 cents to $30.66. WorleyParsons shares fell 26 cents to $22.77, even though the engineering group won a contract to build an oil sands project in Canada. At midday the benchmark S&P/ASX 200 index had lost 6.9 points, or 0.13 per cent, at 5244.3. The broader All Ordinaries index was 8.1 points, or 0.15 per cent, lower at 5237.1. The September share price index futures contract was down 11 points at 5245 points with 69,775 contracts traded. AAP, Reuters