The USD/JPY pair fell from 157.45 to around 156.35 during the Asian session on Wednesday (September 30), touching a one-week low with a decline of about 0.7%.

This move was mainly driven by fund flows tied to Japan's fiscal half-year-end on September 30, as Japanese investors repatriated capital and exporters sold foreign currencies.

Remarks from Japanese and US officials also helped limit gains in the currency pair. Fed's Williams said on Tuesday there is no need to rush another rate hike, although he noted a further increase later this year could be appropriate if the economy evolves as forecast.

Half-Year End Flows Are the Main Driver, the Yen's Strength May Be Hard to Sustain

The USD/JPY pair dropped from around 157.5 to roughly 156.4 during the Asian session on Wednesday, a decline of about 0.7%, while other Japanese yen crosses also weakened in tandem.

This move was mainly driven by fund flows associated with Japan's fiscal half-year-end on September 30, with Japanese investors concentrating on repatriating capital and exporters selling foreign currency.

Selling continued after the Tokyo fix, the daily reference rate set in the middle of the morning session and historically a focal point for corporate fund flows.

Half-year end flows are the dominant driver, and such seasonal moves often reverse quickly once the new fiscal half begins, meaning the yen's gains may be less durable than the headline decline suggests.

Traders are broadly watching how the pair performs on Thursday when the new fiscal half kicks off, as repatriation flows may fade quickly and market liquidity will return to normal.

Historical experience shows that the half-year end effect is usually short-lived, and if fundamentals do not change fundamentally, the USD/JPY pair is likely to strengthen again after the flows subside.

Overall, the yen's current appreciation is more a combination of technical and seasonal factors rather than a clear signal of a trend reversal.

US and Japanese Officials' Comments Limit USD/JPY Upside

Official comments also helped cap the upside for the USD/JPY pair.

Market comments pointed to remarks from Japanese and US officials late last week and earlier this week, with reports that Trump expressed concern about yen weakness fueling speculation of another joint US-Japan intervention.

Japanese Ministry of Finance officials stressed vigilance over excessive exchange rate volatility, and the US side also conveyed signs of concern.

The USD/JPY pair consolidated around 157.5 on Tuesday after rebounding from a one-week low, while hawkish Bank of Japan policy expectations also supported the yen.

These official remarks kept traders cautious about pushing the USD/JPY pair higher, and the pair had been at the upper end of its recent range before the decline.

Rising intervention risk significantly raised the cost of short positions, and market sensitivity around the 160 level increased markedly.

In sum, policy communication has become an important short-term constraint, curbing further sharp dollar strength while also providing extra support for the yen, with traders more inclined to stay on the sidelines or reduce positions on rallies near key resistance levels.

Williams Says No Urgency, But Other Fed Officials Are More Hawkish

Fed officials' remarks added to the dollar's softer tone.

New York Fed President Williams said on Tuesday there was no urgency after the central bank's September rate hike, though he added that another increase later this year could be appropriate if the economy evolves as he forecasts.

Some reports described the remarks as dovish and said they pushed the dollar index slightly lower, even though the index still closed higher that day.

Other Fed officials were more hawkish, with Governor Barr saying further rate hikes may be needed, and money markets still see a relatively high probability of a rate increase at the October meeting.

Williams' phrase "no urgency" removed some support for the dollar, but US Treasury yields remained elevated and overall rate hike expectations stayed firm.

This internal divergence in stance makes the dollar's path more complicated: it faces pressure in the short term from dovish voices, while in the medium term it is supported by hawkish signals and yield advantages.

The market will continue to weigh the relative importance of different officials' comments and the role of upcoming data in confirming the policy path.

Yen Strength Ignores Weak Domestic Data, Flows Rather Than Fundamentals Dominate

The yen's appreciation ignored weak domestic data.

Japan's industrial output fell 1.7% month-on-month in August, against expectations of a 1.7% rise; retail sales rose 2.7% year-on-year, below the expected 3.3%.

These results would normally weigh on the yen by complicating the case for tighter policy, suggesting that flows rather than fundamentals are driving this move.

The Bank of Japan raised its policy rate to 1.25% in September, the highest since 1995, and a former BOJ executive director put the probability of another rate hike in October at 20% to 30%.

The BOJ's own path is another swing factor, with markets debating whether it will act again in October.

(USD/JPY daily chart, source: Yihuitong) As of 12:05 Beijing time, the USD/JPY pair was quoted at 156.82/83.