The dollar has lost about US6c in the past fortnight due to lower interest rates, concerns about the Australian and Chinese economies and signs of improvement in the US.

The Australian dollar has dropped sharply over the past two weeks. It's fallen 6 cents against the US currency, taking it to lows not seen since early last year.

The Australia dollar opened below 99 US cents for the second straight session, driven lower by growing investor demand for the United States dollar and a negative response to Tuesday's federal budget.

The Australian dollar is higher but is failing to build onto its gains as commodity prices fall. At 1200 AEST on Thursday, the local unit was trading at 98.99 US cents, up from 98.72 cents on Wednesday.

With the Australian dollar now firmly trading below parity with the US dollar the benefits to the wider national economy will not immediately help its airlines and will drive changes in their strategies, outlooks and opportunities.

The All Ordinaries added a third of a per cent to 5,160 and the ASX 200 matched that gain to 5,181. The dollar has fallen by around six cents against the greenback over the past three weeks and is also down against a range of other currencies.

Analysts say the strength in the greenback as the outlook for the U.S. economy improves and concerns about growth in China, Australia's most important trading partner, explain the change of fortunes for the Australian dollar. Billion dollar Soros bet ...

The Australian dollar has fallen to a new 11-month low, after US stocks lost ground on the back of another batch of weak economic data.

The government forecast an 18 billion Australian dollar ($17.91 billion) deficit for the 2013-2014 fiscal year, with no return to surplus expected until the 2015-2016 fiscal year.

The Australian dollar has fallen to another 11-month low as the currency becomes unpopular with Japanese investors. On Friday morning, the Australian currency dropped as low as 97.53 US cents, its weakest level since June 2012.