Trading volume in CurrencyShares Australian Dollar Trust (NYSEArca: FXA) was about seven times the average on Wednesday as the currency ETF tries to break a key resistance level. A breakout would be a bullish sign for commodities and the global economy.

More than 1.1 million FXA shares traded Wednesday, compared with average volume of about 166,000 shares over the past three months.

The currency fund is designed to track the movement of the Australian dollar against the U.S. greenback. It tends to be sensitive to commodity prices and emerging markets.

“Because of the Australian economy’s heavy reliance on mineral wealth, its currency often rises and falls with commodities. The Australian dollar has maintained a strong correlation with diversified commodities prices,” Morningstar says in a profile of FXA.

A big jump in China’s trade surplus buoyed the Australian dollar as dealers bet that the world’s second biggest economy is recovering quicker than expected, Dow Jones Newswires reported Wednesday.