The benchmark S&P/ASX200 index at 11.08am AEST on Tuesday climbed to 8,148.8, a smidge over its old intraday record of 8,148.7 set on August 1.
At noon AEST it was hovering just under that level, up 26 points, or 0.32 per cent, at 8,147.6.Â
IG market analyst Tony Sycamore said that a sustained close of over 8,150 would pave the way for the rally to continue to around 8,230-8,250, while a failure to sustain the break above 8150 would keep the ASX200 range-bound with scope to re-test last week's 7,198 low.
The gains come ahead of this week Federal Reserve meeting, with hopes rising that the US central bank's rate-setting committee will opt for a double-sized interest rate cut when it hands down its decision early on Thursday AEST.
At midday nine of the ASX's 11 sectors were higher, with consumer staples and telecommunications down slightly.
Energy was the biggest mover, up 0.8 per cent, in a turnaround after recently underperforming the rest of the market.
Woodside had climbed 1.0 per cent, Santos had added 0.6 per cent and New Hope had gained 3.3 per cent as the coalminer reported it made a $476 million profit in the year to July 31, down 56 per cent from last year.
New Hope chief executive Rob Bishop said the company had delivered on its organic growth pipeline, including the restart of operations at its New Acland mine in Queensland, which it plans to ramp-up this year.
In the tech sector, Xero had gained 1.6 per cent to a nearly three-year high of $146.76 after the Kiwi cloud accounting company said it was spending $US70 million to acquire Syft Analytics, a Johannesburg-based cloud-based analytics platform for accountants and small businesses.
Xero chief executive Sukhinder Singh Cassidy said that Syft, which is used to review, analyse and forecast financial outcomes, would continue to exist as a standalone offering post-acquisition.
In the financial sector, the big four banks were mixed, with Westpac up 0.7 per cent and CBA edging 0.1 per cent higher, while ANZ and NAB had both dipped 0.3 per cent.
In the heavyweight mining sector, BHP was up 0.3 per cent, Fortescue had climbed 1.6 per cent and Rio Tinto had grown 0.5 per cent.
The Australian dollar meanwhile was at a two-week high against its weakening US counterpart, buying 67.52 US cents, from 67.22 US cents at Monday's ASX close.