Aust stocks close slightly lower

The Australian stock market ended its long run of gains to close slightly lower as investors wait for the US Federal Reserve's decision on reducing stimulus.

At the official market close of 1615 AEST, the benchmark S&P/ASX200 index fell 0.25% to 5,238.1 points, while the broader All Ordinaries index was 0.28% lower at 5,230.4 points.

IG market analyst Stan Shamu said the market was biding its time ahead of the Federal Market Open Committee announcement, due at 0400 AEST Thursday morning.

"There is clearly indecision heading into the FOMC meeting," he said.

"After a mildly firmer open, the local market has lost some ground with no confidence to hold on to positions at elevated levels."

Materials led the slump amid falling iron ore and gold prices, he said, while the big banks were in the black after Bank of America Merrill Lynch upgraded National Australia Bank's stock to buy (from underperform).