The benchmark S&P/ASX200 was up 34.2 points, or 0.40 per cent to 8,621.4 by midday on Wednesday, topping the Valentine's Day record of 8,615.2 points and building on the previous day's record close.
The broader All Ordinaries was up 34.9 points, or 0.40 per cent, to 8,847.4, just 35 points shy of its intraday record of 8,882 points, also set on February 14.
The uptick followed a positive session on Wall Street and came after officials from the US and China agreed on an in-principle framework to resolve export restrictions on rare earths and magnets.
Details on the agreement remained light, and it still required approval from US President Donald Trump and China's President Xi Jingping, IG Markets analyst Tony Sycamore said.
"If the two presidents review and approve the outcome of today's trade talks, it will likely include maintaining the reduction in US tariffs on Chinese goods at 30 per cent (down from 145 per cent) and Chinese tariffs on US goods at 10 per cent (down from 125 per cent)," he said.
The de-escalation in US-China tensions helped lift large cap miners Fortescue (up two per cent) and BHP (up 1.8 per cent), but Rio Tinto continued to be the laggard of the iron ore giants, grinding 0.3 per cent higher.
Materials stocks were among the best performing sectors, up 0.7 per cent, as energy stocks pushed 0.8 per cent higher and real estate lifted one per cent.
Only two of 11 local sectors - IT and utilities stocks - were in the red by midday.
Gold miners were down again as the precious metal continued to consolidate at around $US3,350 ($A5,140) an ounce.
The US-China rare earths "agreement" weighed on local miners of the minerals, with Lynas Rare Earths the top-200's worst performer and down more than six per cent in early trade.Â
An 0.8 per cent lift in energy stocks was helped by a more than two per cent charge from Woodside to $23.56, as oil prices rolled over after hitting seven week highs on Tuesday.
Commonwealth Bank hit a fresh record high for a second day in a row, reaching $183.19 before easing to $182.46 and taking its value to $305 billion.
CBA's big three competitors traded either side of flat as investors tempered their appetite for Australian banks' famously lofty valuations.
The financial sector is trading at record levels, up 0.2 per cent for the day and up by more than 25 per cent since early April's post-"liberation day" lows.
Buy now, pay later provider Zip Co was leading the top-200, rallying 14.4 per cent after upgrading forward guidance on the back of strong growth in its US business.
Qantas has slipped 1.2 per cent to $10.52 after announcing it will close Jetstar Asia, its Singapore-based intra-Asia airline, due to weak earnings.
The airline will redeploy 13 aircraft to Australian and NZ.
The call comes two weeks before its domestic rival Virgin Australia relists on the Australian Securities Exchange.
Local technology stocks took a breather after rallying on Tuesday, shedding 0.2 per cent, but data centre plays were still pushing higher, with Megaport and NextDC both up more than 1.7 per cent each.
The Australian Dollar is buying 65.04 US cents, up from 65.12 US cents on Tuesday at 5pm.
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