Australian shares opened lower on Monday despite Wall Street edging to fresh records, with the S&P 500 notching another closing high driven by a rally in chipmakers. The ASX 200 fell 0.3% to 8,675 points while the Australian dollar weakened 0.14% to 72.38 US cents, creating a mixed picture for trans-Tasman markets.

The divergence comes as investors await Australia's federal budget, with particular focus on potential tax changes that could impact market sentiment. Oil prices rose following setbacks in efforts to end the US-Iran conflict, keeping concerns about the Strait of Hormuz and fuel costs in focus, while spot gold gained 0.6% to $US4,761 per ounce amid ongoing geopolitical tensions.