At lunchtime AEDT on Wednesday, the benchmark S&P/ASX200 index was up 18.4 points, or 0.22 per cent, to 8,332.4, while the broader All Ordinaries was up 23.1 points, or 0.27 per cent, to 8,581.4.
The outcome of the Fed meeting will be announced in Australia's pre-dawn hours on Thursday, with Capital.com analyst Kyle Rodda predicting the equities markets' Santa rally would live or die on the central bank's commentary, guidance and projections.
Seven of the ASX's 11 sectors were higher at midday, with telecommunications flat and the bourse's two consumer sectors and financials lower.
The interest rate-sensitive property sector was the biggest mover, climbing 1.2 per cent. Charter Hall and GPT Group were both up 1.8 per cent and Goodman Group had risen 1.4 per cent.
In the financial sector, Omni Bridgeway had soared 47.4 per cent to an eight-month high of $1.425 after the litigation funder announced it would sell 70 per cent of its funds to US-based alternative investment manager Ares Management Corporation for $310 million.
The big four banks were mixed, with CBA down 0.7 per cent, Westpac up 0.7 per cent, NAB edging 0.1 per cent lower and ANZ basically flat.
In the heavyweight mining sector, BHP was up 0.6 per cent, Rio Tinto had grown 1.0 per cent and Fortescue had added 0.5 per cent.
In health care, Clarity Pharma had grown 16.1 per cent to a one-week high of $5.35 after the radiopharmaceutical company announced it had developed a new product potentially targeting tumours.
On the flip side, Percheron Therapeutics had plunged 86.4 per cent to an all-time low of 0.8 cents after a Phase 2b clinical trial indicated its lead drug candidate was no better than a placebo in improving outcomes for boys with Duchenne muscular dystrophy.
"In the more rigorous environment of a randomised, placebo-controlled international study, avicursen has not performed in a way that we had been led to expect by earlier studies," Percheron chief executive James Garner said.
