Speculators in yen futures extended a net long position in the week ended June 29, data from the Commodity Futures Trading Commission showed on Friday.
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, especially if that position conflicts with the positioning of the more influential commercial players.
Speculators are generally trend followers seeking to pick a precise top or bottom in the market.
In the latest week, speculators grew the net long yen position to 8,416 contracts from 5,495 a week earlier. It was the largest net long position since the April 12 report, which saw a net long of 24,760 contracts.
During the CFTC's reporting period, September yen futures inched up to a close of $0.009265 on June 29 from a close of $0.009241 on June 23.