At noon AEDT on Wednesday, the S&P/ASX 200 index was up 59.5 points, or 0.7 per cent, to a week-long high of 8191.3 points. The broader All Ordinaries was 60.7 points higher, or 0.7 per cent, to 8448.5.
Westpac economist Jameson Coombs said it could be a some time before a final result out of the US, given it was a tight race between Republican candidate Donald Trump and Democratic rival Kamala Harris.
"Still, markets are likely to be volatile and reactive to headlines on the progress of votes," he wrote in a note.
US equities performed strongly overnight, with the tech-heavy Nasdaq-100 index climbing 1.7 per cent. Nvidia was 2.8 per cent higher, nudging the chipmaker in front of Apple as the world's biggest company with a market cap of US$3.42 trillion.
Later in the week, the Federal Reserve is tipped to deliver a 25 basis point interest rate cut, with a gradual approach to easing expected given few signs of recession.
Back at home, the Reserve Bank of Australia kept interest rates on hold at its meeting on Tuesday, as was widely expected, though it did not rule out the possibility of another hike despite lightly downgrading its economic forecasts.
All ASX sectors were trading higher at midday, with consumer discretionary stocks leading the charge, up 1.2 per cent, with JB Hi-Fi up 2.2 per cent and Wesfarmers 1.6 per cent higher.
Each of the four major banks were trading higher, with ANZ up 0.3 per cent, Westpac had risen 0.8 per cent, NAB had gained 1.1 per cent, and CBA shares were 0.7 per cent higher.
The big miners were also in the black in line with a higher iron ore price, with Rio Tinto one per cent higher, BHP had gained 0.7 per cent, and Fortescue was up 0.2 per cent.
Goodman Group shares recovered after falling earlier in the session after releasing an operating update, to be up 0.4 per cent at midday. The board confirmed its forecasts for operating earnings per share to lift 9 per cent in FY25 and a full-year distribution of 30 cents.
Meanwhile, the Australian dollar was buying 65.87 US cents, down from 65.98 US cents at Tuesday's ASX close.