The European Central Bank was informed of the United States' decision to sell euros in order to buy yen only after the trade had already been executed, the Financial Times reported on Thursday, citing several people familiar with the matter. Reuters said it could not immediately verify the report.

The disclosure relates to last Friday's rare joint intervention by Japan and the United States, in which authorities bought yen in a historic operation aimed at shoring up the currency after its sustained slide. The yen's weakness has been driven by a persistent and wide interest rate gap between the Bank of Japan's ultra-loose monetary policy and the Federal Reserve's higher-rate stance, which has encouraged capital flows out of yen and into higher-yielding currencies. As part of the intervention action, the US reportedly sold euros to help fund its yen purchases — a step that, according to the FT's sourcing, was not communicated to the ECB in advance.

Both Tokyo and Washington vowed at the time to take further action if needed to support the yen, underscoring the scale of concern among policymakers over the currency's weakness. The intervention was described as historic in scale, and officials warned that additional measures could follow if necessary. Joint US-Japan currency interventions are themselves uncommon events, with only a handful occurring over the past several decades, typically reserved for moments of acute disorder in foreign exchange markets.

The timing gap described in the FT report — with the ECB learning of the euro-selling component only after execution — raises questions about how tightly coordinated the operation was beyond the two directly involved countries, even though the intervention itself was carried out jointly and publicly by Japan and the US. The episode points to a narrowly coordinated bilateral operation rather than a broader multilateral effort, which may prompt currency market participants to question how much advance alignment existed among major central banks before the intervention took place. The Group of Seven industrialized nations has long functioned as the primary forum for consultation on currency matters among allied economies, making the absence of prior ECB notification a notable departure from that consultative tradition.

The lack of prior ECB input could introduce uncertainty around euro positioning, given that the trade directly involved selling euros to fund yen purchases without the ECB's prior knowledge.

The US decision to fund the trade with euros is likely to be perceived as an unprecedented break from long-standing norms of cooperation among Western monetary authorities. Since World War II, Western central banks and finance ministries have generally operated on mutual trust and consultation, with currency market interventions typically coordinated in advance among allied institutions.

According to the FT, the US chose euros over dollars specifically to avoid the trade being interpreted as an attempt to weaken the dollar — a move that would have clashed with Treasury Secretary Bessent's strong-dollar stance.

Related: Yen intervention data shows scale of Japan's fight against 40-year lows