The benchmark S&P/ASX200 index was up 27.4 points, or 0.39 per cent, to 7,120.4 at noon, while the broader All Ordinaries had gained 31.8 points, or 0.43 per cent, to 7,358.
The gains came despite modest losses on Wall Street, where the S&P500 closed down 0.4 per cent.
The materials and energy sectors have been the standouts so far, rising 2.1 and 1.2 per cent respectively on the back of a climb in the price of iron ore and crude oil.
Santos and Woodside were both up two per cent in advance of the latter's annual general meeting on Thursday, while Whitehaven Coal had risen 5.1 per cent to an all-time high of $5.16 on the back of an ongoing share buyback.
Fortescue Metals was up 2.5 per cent and Rio Tinto 1.8 per cent. BHP had advanced 0.7 per cent.
Brambles had given back two-thirds of yesterday's gains after the global pallet company advised that European private equity giant CVC Capital Partners would not be pursuing a takeover offer after all, "due to the current external market volatility".
Brambles was down 7.6 per cent to $10.72.
James Hardie fell 4.0 per cent to a one-year low of $37.28 after the building products company announced sales of US$3.6 billion in the 12 months to March 31, up 24 per cent from a year ago but slightly below market expectations.
The company reaffirmed its FY2023 guidance of $US740 million to $US820 million in net income.
The big banks were all higher, with CBA gaining 1.8 per cent and the others between 0.4 and 0.8 per cent.
The healthcare and property sectors were both down by about 1.2 per cent. CSL had fallen 1.3 per cent.
5°C