US Treasury Department has informed banks that it might make currency trades on Friday to support the JPY, reports WSJ citing sources; Some banks were told to have executable trades ready to exchange JPY for euros

Direct US participation in yen-supportive intervention is historically rare; the norm has been for Japan's Ministry of Finance to act alone in USD/JPY, with the Treasury's role confined to rhetorical endorsement or, on isolated occasions, coordinated G7-style operations in extraordinary circumstances such as post-disaster yen strength. The reported instruction to banks to stand ready to exchange JPY for euros is the unusual feature: in past coordinated episodes the counterpart leg has typically been dollars, and a euro leg would imply either a cross-currency construction or a broader multilateral framing, both of which would break with the standard playbook. The tell in prior episodes has been the advance warning to dealers itself, since authorities seeking maximum effect have historically preferred surprise, while advance notice has more often preceded symbolic or size-limited operations. What distinguishes durable from failed interventions historically is whether the action leans with the interest rate differential or against it; operations fighting an unchanged policy gap have tended to be retraced, while those timed near a shift in the rate outlook have held. Follow-ons worth noting are confirmation from the Japanese side, any sizing, and whether the euro leg is executed as reported or reshaped before Friday.