【Midnight Volatility】From Mimura's sharp plunge to a "full rebound" mystery―― Focus on US interest rate 5.27% · Oil at $108 vs Iran sanctions relief reports and Trump's announcements
In the early hours of September 29, 2026, the USD/JPY dollar-yen exchange rate is swinging wildly like a roller coaster.
Under strong intervention warnings from Finance Minister Mimura, it brieflyfell to 156.62 yenbut thereafter, with the backdrop of rising crude oil prices and a sharp rise in U.S. long-term rates,almost fully recovered to around 157.50 yen. However, soon after, CNN reported that President Trump was positive about easing sanctions on Iran, and againpushed back toward around 157.20 yen.
“Why did the yen spike back to the mid-157s in an instant after Mimura’s remarks?”
“Will Trump’s ‘major announcement’ tonight move the market?”
We will succinctly and clearly organize the rapidly changing late-night market dynamics and the key points you should keep in mind tonight.
1. The oil at $108 and U.S. rate at 5.27% that instantly absorbed the Mimura shock
In a Reuters interview, Finance Minister Mimura stated that the message shared by both the Japanese and U.S. governments that underestimating the yen is problematic was very clear, and that the stance to continue currency intervention and policy responses remains firm, not being satisfied or assured by the current exchange rate.
As a result, the dollar-yen was driven down to 156.62 yen, but it was forcefully pushed back up to 157.50 yen bythe surge in U.S. rates and oil.
Brent crude:soared temporarily into the high $108s
U.S. 10-year yield:rose to around 5.27%
A powerful dollar-buying spiral—“Iran rejection of a ceasefire ➔ prolongation of the Strait of Hormuz closure ➔ oil spike ➔ resurgence of U.S. inflation ➔ expectations of further Fed rate hikes”—was unleashed and instantly offset Mimura’s yen-buying remarks.
2. The “laddering out of the dollar” on Iran sanctions relief news
However, at the point it had rebounded to around 157.50 yen, a new headline hit.
CNN reported that President Trump was positive about easing sanctions related to Iran’s nuclear issue, which sparked expectations of de-escalation in Middle East tensions and stabilization of oil prices. With expectations for a decline in U.S. long-term rates, the dollar was sold, and it was pushed back to around 157.20 yen.
What truly governs the market is not mere jawboning but the thick linkage of “Middle East situation ➔ oil ➔ U.S. long-term rates.”
3. The truth about Trump’s “major announcement”—if it is a pure steel project, the exchange rate will be calm
The late-night around 3 a.m. announcement has sparked various guesses, but information from White House sources indicates the announcement is about a roughly $15 billion steel plant project in Iowa.
【Announcements known in advance】
・A colossal steel plant in Iowa with about $15 billion in investment (Mesabi Metallics)
・Scheduled to operate in 2030, with annual capacity of 7.5 to 10 million tons ・Permanent employment around 1,750 people
How to gauge the impact on the exchange market
In short, if the announcement is only about the steel plant project, the impact on the USD/JPY is virtually neutral (at most a momentary reaction). Its operation is planned for 2030, and it is not large enough to move near-term U.S. payrolls or Federal Reserve policy decisions.
The market moves only when there are additional policy elements such as the following “plus α”s announced simultaneously.
A declaration of a large-scale addition of tariffs on steel and essential goods.- to be announced
Remarks that directly affect inflation, fiscal spending, or Federal Reserve rate policy
Surprise mentions regarding Middle East or Iran
Without such additional factors, the likelihood is high that the material will fizzle out and the market will move on.
Summary: Tonight’s trading perspective
Tonight’s market is dominated by three competing forces vying for control in rapid succession.
A strong yen-weakness restraint from Finance Minister Mimura (downward pressure toward the 156 range)
Oil at $108 and U.S. rate at 5.27% (upward pressure toward mid-157s)
Iran sanctions relief news (reversal of dollar due to Middle East risk relief)
Rather than overreacting to Trump’s announcement itself, focus on how the prices of oil and the U.S. 10-year yield react after the announcement, in either direction.
If U.S. rates drop from the 5.2% range and oil softens, the defense line at “156.50 yen” could be tested again. Do not be swayed by late-night volatility; observe objective price action and trade with discipline.
If you found this helpful at all, please follow us to receive updates!
Your support motivates updates!
An indicator that excludes emotions and captures the market with clear evidence and rules.
Details of function and design logic are published on each product page
? [GogoJungle product page]
https://www.gogojungle.co.jp/users/723420/products
