Bank of America Global Research discusses the scope of Japan's JPY intervention on Thursday.

JPY intervention was likely sizeable…

"In line with our expectations, the BoJ struggled to deliver a "hawkish hold" which, alongside higher oil prices, pushed USDJPY above 160. On Thursday, an escalation of currency rhetoric by Japan officials, including FM Katayama, preceded a collapse in spot. The fact that USDJPY's sell off exceeded that of prior large USD selling interventions in '22 and '24 all but confirms reports of FX intervention," BofA notes.

… but '26 ≠ '24

"While the '24 interventions proved effective in hindsight (USDJPY fell ~13% between July and September), we expect the latest move to be less durable  Spillover to broader risk sentiment has been limited too, compared to '24, partly because yen-funded carry trades have been less prevalent, according to our metrics.

Fading JPY strength is akin to catching a falling knife, but prudent in our view, especially since historical interventions have tended to be one-off (no more than a couple of days) rather than persistent," BofA adds.