Every three years, when the BIS releases its new foreign-exchange market survey, the WSJ Dollar Index will be reweighted using the bank's latest trading volume figures, making it a dynamic index that evolves with the constantly changing market.

WSJ: WSJ, FX Trader Launch Dollar Index

The index is proportionally weighted based on foreign-exchange trading volume data from the Bank for International Settlements' triennial central-bank survey on global foreign-exchange market activity.

WSJ: WSJ, FX Trader Launch Dollar Index