The value of the dollar's net long position fell to $38.77 billion in the week ended June 12 from $39.65 billion the previous week.
Short euro positions declined to 195,187 contracts from 214,418 contracts a week earlier.
Speculators significantly boosted their bets against sterling in the latest week to 23,112 contracts, the highest since mid-March, from 2,867 a week earlier.
They also increased their bets in favor of the yen to 12,307 contracts, the highest since February.
To be short a currency is to bet it will decline in value, while being long is a view its value will rise.
The Reuters calculation for the aggregate US dollar position is derived from net positions of International Monetary Market speculators in the yen, euro, British pound, Swiss franc, and Canadian and Australian dollars.