Both of the mining giants lost ground; BHP shed 1.8% and Rio Tinto lost 1.5%.
All four of the big banks weakened; ANZ and Westpac gave up around 1% each.
Elsewhere in the financial sector, ASX slipped 0.3% after its full-year result matched expectations.
AMP was a bright spot, climbing 2.7% after its 1H11 underlying profit topped estimates.
Wesfarmers also beat analyst forecasts with its $1.9 billion profit. WES shares advanced 0.3%, although at one stage were up more than 3%.
The ASX 200 dropped 53 points (-1.2%), settling at 4251.