U.S. Dollar Index

The US Dollar Index (USDX, DXY) is an index (or measure) of the value of the United States dollar relative to a basket of foreign currencies, often referred to as a basket of US trade partners' currencies.

It is a weighted geometric mean of the dollar's value relative to other select currencies:

USDX goes up when the US dollar gains "strength" (value) when compared to other currencies.

USDX started in March 1973, soon after the dismantling of the Bretton Woods system. At its start, the value of the US Dollar Index was 100.000. It has since traded as high as 164.7200 in February 1985, and as low as 70.698 on March 16, 2008.

The make up of the "basket" has been altered only once, when several European currencies were subsumed by the euro at the start of 1999. The make up of the "basket" is overdue for revision as China, Mexico, South Korea and Brazil are major trading partners presently which are not part of the index whereas Sweden and Switzerland are continuing as part of the index.