Basket Of USD Shorts

Tammy Trader expects a decrease in the value of the dollar. She shorts it (sells in anticipation of depreciation) against a group of foreign currencies, known as a "basket." In Tammy's rationale, if the dollar appreciates, it will likely appreciate at different rates against the other currencies she's purchased, thereby lessening her loss due to the varying strengths of the currencies involved.

Conversely, had she shorted it against only a single currency, she would have risked the value changing more drastically, resulting in an increased risk (or potential gain) for her position. Buying a basket essentially diversifies her arsenal of currencies.