THE Australian dollar closed marginally weaker after a thin trading day in which the local unit was unmoved by mixed economic data.

At 1700 AEDT, the Australian dollar was trading at $US0.9126/29, down from yesterday's close of $US0.9154/57.

During the domestic session, the local unit traded between $US0.9126 and $US0.9164.

"It's marginally lower but it's fairly close (to last night's close),'' Commonwealth Bank associate economist Sara Hoenig said.

"There was a moderate reaction to the balance of payment data today, but it traded in a thin range.

"Equities haven't made much of a move and that's kept it in a tight range, too.''

The current account deficit expanded to a seasonally adjusted $16.18 billion in the September quarter from a revised $13.13 billion in the previous quarter, the Australian Bureau of Statistics (ABS) said on Tuesday.

The result was slighter smaller than the median forecast for a deficit of $16.8 billion.

Exports of goods and services fell by 2.3 per cent, while imports were up by 5.8 per cent in the quarter.

The drop in exports and a switch in supply from local producers to foreign suppliers will knock an estimated 1.8 per percentage points from the September quarter gross domestic product (GDP), the ABS said.

Meanwhile, the Australian share market closed marginally weaker amid relatively quiet trading, with financial stocks slipping into the red on the prospect of higher interest rates pushing up bad debts.

At 1615 AEDT, the benchmark S&P/ASX200 index was down 5.9 points, or 0.13 per cent, at 4670.6, while the broader All Ordinaries had slipped 8.8 points, or 0.19 per cent, to 4686.4.

On the Sydney Futures Exchange, the December share price index contract had declined two points to 4674, on volume of 22,249 contracts.

Patersons Securities associate director John Curtin said market turnover was below average and profit-takers were pushing banks lower on worries that higher interest rates could lead to a rise in bad debts.
 
Commonwealth Bank led the major banks lower, shedding 70 cents, or 1.3 per cent, to $53.09, while National Australia Bank lost 11 cents, or 0.39 per cent, to $27.89.

Westpac fell four cents, or 0.17 per cent, to $23.85 and ANZ Banking Group dropped two cents to $21.93.
 
Oil Search fell six cents to $5.84 and Santos declined seven cents to $14.68.

Resources giant BHP Billiton gained 44 cents to $41.05 and rival Rio Tinto added 31 cents to $71.90.