At noon AEDT on Monday, the benchmark S&P/ASX200 index was up 16.7 points, or 0.2 per cent, to 8,452.9, while the broader All Ordinaries had risen 12.4 points, or 0.14 per cent, to 8,451.5.
Earlier in the morning, the ASX200 had been within 11 points of its all-time intraday high, set on Thursday.Â
A close at this level would also break Thursday's record closing high of 8,444.
Nine of the ASX's 11 sectors were higher at midday, with utilities and health care lower.
Tech was the biggest gainer, up 1.2 per cent as Nextdc rose 2.5 per cent and Wisetech Global climbed 1.5 per cent.
In the heavyweight mining sector, De Grey had soared 28.1 per cent to $1.9475 and Northern Star had dropped 5.9 per cent to $16.485 after the latter agreed to acquire the former in a $5 billion all-scrip transaction.
"The acquisition of De Grey is strongly aligned with Northern Star's strategy and contributes to our purpose of generating superior returns for shareholders," said Northern Star managing director and chief executive Stuart Tonkin.
The combined group would be among the world's 10 biggest goldminers, the companies said.
Other goldminers were down as the precious metal slid $US20 to $US2,637 an ounce, with Newmont and Evolution both falling 2.0 per cent.
Elsewhere in the sector, BHP was up 0.5 per cent while Fortescue and Rio Tinto had both grown 1.1 per cent.
In the financial sector, GQG Partners was down 13.2 per cent after UBS downgraded the stock, estimating the firm could have lost more than $600 million in funds under management following the US indictment of India-based Adani Group.
The big four banks were all higher, with ANZ up 0.8 per cent, NAB rising 0.5 per cent and Westpac and CBA both edging 0.1 per cent higher.
The Australian dollar was buying 65.03 US cents, from 65.07 US cents at Friday's ASX close.
