Speculators in IMM euro futures trimmed a net long position in the week ended August 31, data from the Commodity Futures Trading Commission showed on Friday.
"Long" positions are effectively bets that a specific currency will rise.
The data from the CFTC's Commitments of Traders report on speculative positioning are used by analysts as an indicator of future market direction.
For example, extreme net long speculative positions often signal a decline in the currency going forward, especially if that position conflicts with the positioning of the more influential commercial players.
Speculators generally are trend followers seeking to pick a precise top or bottom in the market.
Euro futures speculators cut the net long position to 20,827 contracts from 24,616 contracts in the previous week.
During the CFTC's reporting period, the euro rose very slightly to a close of $1.2185 on August 31 from a close of $1.2181 on August 25.