The Bank of Japan’s projection for money market conditions for the following day indicated a 4.51 trillion yen net outflow of funds, compared with brokerage forecasts of between zero and an increase of 500 billion yen.

Yen-buying activity involves the BOJ soaking up the currency from markets, so any outsized shortfalls in funds can offer an estimate of the size of any intervention.

Japan stepped into markets last Thursday to shore up the yen from a near two-year low against the dollar, sources told Reuters, seeking to halt a slide worsened by an energy shock related to the Iran war. BOJ data indicated that the cost of the operation was as much US$35 billion.

Traders suspected that three more jolts in the currency pair through Wednesday of this week marked further intervention. With Japan closed for a three-day holiday, the latest BOJ figures imply the operations may have occurred across several sessions.

Japan faces no constraints on how often it can intervene in markets and is in daily contact with US authorities, top currency diplomat Atsushi Mimura said on Thursday.

Japan’s most recent officially confirmed intervention happened in July 2024, when it spent about US$36.8 billion to bolster the yen after it sank to a 38-year low of 161.96 per dollar.