Aussie shares fall ahead of Reserve Bank meeting

The RBA is seen as all but certain to leave rates unchanged Tuesday afternoon, with 42 of 42 experts and economists polled by Finder predicting a hold.

But traders will be watching to see if the RBA maintains its hawkish stance such as language that the board "is not ruling anything in or out," especially after the US Federal Reserve enacted a double-sized rate cut last week.

The Australian dollar had climbed to its highest level since December against its US counterpart ahead of the meeting.

Seven of the ASX's 11 sectors were lower at midday, and four were higher.

Consumer staples were the biggest mover for a second day as Coles and Woolworths continued losing ground following the Australian Competition and Consumer Commission announcing Monday it was launching legal action against the two supermarkets for allegedly misleading discounting claims.

Woolworths shares were down 2.6 per cent to a three-month low of $32.93, while Coles was down 2.5 per cent to a six-week low of $18.12.

On the flip side, uranium developers were for a second day posting some of the strongest gains in the ASX200, after a US utility announced plans to reopen the shuttered Three Mile Island nuclear reactor to power Microsoft's energy-hungry AI operations.

Boss Energy had climbed 10.2 per cent, Paladin Energy was up 8.2 per cent and Deep Yellow was 7.3 per cent higher.

Elsewhere, online fashion retailer Cettire had soared 46.2 per cent to a three-month high of $1.95 after auditor Grant Thornton finally signed off on its accounts after a one-month delay. 

Fletcher Building was up 7.7 per cent to a four-week high of $2.72 after the Kiwi building company completed a $NZ418 million ($A382 million) capital raising.

The heavyweight financial sector was 1.6 per cent lower, with all of the big four banks in the red.

ANZ was down 1.4 per cent, Westpac had dropped 1.9 per cent, CBA had retreated 2.1 per cent and NAB had fallen 2.4 per cent.

But the material sector was up 1.6 per cent, with all the iron ore giants putting in a solid performance after People's Bank of China governor Pan Gongsheng announced a raft of stimulus measures aimed at propping up China's economy.

BHP was up 2.2 per cent, Rio Tinto had gained 3.2 per cent and Fortescue had climbed 1.6 per cent.

Lithum developers were also well in the green, with Liontown up 3.2 per cent and Pilbara advancing 3.8 per cent.

The Australian dollar was at a nine-month high against its US counterpart,  buying 68.40 US cents, from 68.11 US cents at Monday's ASX close.