USD/JPY finally broke below 155 on Sept. 7 after the market had defended the area twice before, first after Golden Week intervention and again after another intervention at the end of July.
By early trading on Sept. 8, the pair was already below 154.50. Once the market slipped through roughly 155.50, the level marking the post-intervention lows from those two earlier episodes, another yen threshold gave way quickly.
In Stephen Innes’ original piece, that break matters for more than the size of the move itself. Markets tend to remember levels that have been defended more than once. A first test can be dismissed as noise. A second test starts to build conviction. By the third, enough positions are often stacked around the idea that the floor will hold again. When it fails, the move can speed up because traders are reacting not only to fresh information, but also to the collapse of confidence built around that line.
Why the 155 level carried weight
The article argues that a third test does not become important merely because it is the third. What matters is what accumulates after the first two successful defenses: more traders begin to recognize the line, more positions are built against it, more stop-loss orders gather behind it, and more breakout traders wait on the other side.
Innes says this is not a statistical law. He traces the idea back to his early days trading USD/JPY at a Japanese bank, where a chief trader was so focused on round numbers and repeated tests that he earned the nickname the "Tokyo round-number prophet." That trader believed the third serious test was often the decisive one, and that once a major USD/JPY level finally gave way, the market rarely looked back until the underlying mechanism itself started to lose force.
He describes that shift as the "Dark Side of the Boom," a point where the broader structure supporting a trade can begin to loosen all at once.
Washington is one source of support for the yen narrative
As for the immediate trigger behind the latest sharp drop, the article says it is still difficult to identify with precision. But since the middle of last week, the macro narrative behind the yen has clearly changed, with several forces now leaning in the same direction.
The first comes from Washington. U.S. Treasury Secretary Scott Bessent has adopted a firmer tone on Japanese fiscal and monetary policy. Around the G20, he argued that Japan should move away from its reflation stance and said he believed the Japanese government and the BOJ would take steps that ultimately strengthen the yen.
The timing stood out. Japanese ministries had just submitted FY27 budget requests totaling about JPY 143 trillion, well above the roughly JPY 122 trillion initial budget for the current fiscal year. That reinforced the impression that Japan’s fiscal backdrop remains highly expansionary. Bessent’s comments may simply have coincided with those figures, but the article notes that in markets, timing is often interpreted almost as carefully as intent.
The message heard by overseas investors was fairly direct: Washington wants a stronger yen, and Tokyo may have less room than before to ignore that preference.
The article says this view was reinforced by reports that Bessent had already voiced dissatisfaction with Japanese economic policy during a May visit, and by a widely held market view that the coordinated intervention at the end of July took place with U.S. cooperation. Whether every detail of that story is accurate is almost secondary in market terms. What matters is that it gives global investors a political framework for expecting Japan to move away from the reflation mix that had helped keep the yen weak for a long time.
The BOJ has not taken rate-hike risk off the table
The second force comes from the BOJ itself.
Bessent met BOJ Governor Kazuo Ueda on the sidelines of the G20. The U.S. Treasury later stressed the importance of policy communication, inflation expectations, and avoiding excessive currency moves.
Ueda then said rate hikes would be fully discussed at every meeting, including the next one. That kept the Sept. 17-18 meeting firmly in view as a live event for possible tightening.
BOJ board member Hajime Takata pushed that shift a bit further. According to the article, he argued that the central bank should be ready to raise rates flexibly rather than be constrained by a pace already priced in by markets. He later played down the odds of a large move at the next meeting, but by then the market had absorbed the more important point: the BOJ may be willing to move faster than investors had previously assumed.
That matters because for much of the summer, long USD/JPY positions rested on a comfortable premise: U.S. rates would stay high, Japanese rates would stay low, carry trades would keep paying, and any yen rebound would struggle to last.
Now that policy gap may be narrowing from both ends.
GPIF speculation has returned
The third leg of the story is less certain, but potentially much larger in scale. The article says speculation has resurfaced over possible changes in the asset allocation of the Government Pension Investment Fund, or GPIF.
GPIF manages about JPY 300 trillion. Even a modest shift toward domestic Japanese financial assets could have a meaningful effect on both local markets and the yen, according to the article.
The issue first surfaced in July, when Finance Minister Satsuki Katayama said the government wanted to explore ways to encourage GPIF and other pension funds to increase investment in Japanese financial assets.
Market interest picked up again after a GPIF board meeting on Aug. 21. A later agenda, the article says, showed discussion of a Basic Portfolio Review Project Team. Reports that this was the first August board meeting in about seven years only added to the room for speculation.
For now, nobody knows whether any meaningful reallocation will actually take place. Details of those discussions may not be made public for months. Still, markets do not always wait for certainty, especially when the institution involved manages JPY 300 trillion. The possibility of capital returning to Japan can influence positioning on its own.
The dollar side has stopped looking as convincing
The article also argues that the dollar leg of USD/JPY has become less compelling just as yen-specific factors have improved.
The August U.S. jobs report was strong, with nonfarm payrolls rising by 162,000. That was enough to revive some probability of another Federal Reserve rate increase. Yet the dollar response was surprisingly muted, and the article treats that as a signal in itself. Normally, payrolls this strong would be expected to push the dollar more clearly higher, especially with markets already discussing a September hike.
Instead, the dollar struggled to build momentum.
Part of the explanation is that Federal Reserve officials, including Christopher Waller, have made clear that they want to see the Sept. 11 CPI report before making a final call. Year-over-year wage growth also slowed to 3.1%, extending its gradual downtrend and reducing the urgency of the argument that the labor market is generating a fresh wave of inflation pressure.
So the payrolls data strengthened the case for a hike, but did not settle it. CPI still holds the decisive vote.
President Trump has been pushing in the opposite direction, calling for lower rates and threatening what the article describes as an illogical Trump-style response if the Fed refuses to cut. Based on current data, a rate cut at next week’s meeting would be difficult to justify, but the political message from the White House is clear enough: it does not want another round of tightening.
That has helped cap the dollar. At the same time, Japan-specific developments have started to support the yen, which is why the article says this move feels different from earlier intervention-driven rebounds. Pressure is now coming from both sides of the pair: Japan is turning more hawkish, or at least being seen that way, while one of the dollar’s strongest supports is fading.
Technically, the break opens lower levels back into view
From a technical standpoint, the break below 155 carries added significance because USD/JPY also moved through the 38.2% retracement of the rise from the April 2025 low above 139.50 to the July 2026 high just below 164.
That puts the January low below 152.50 and the 50% retracement area above 151.50 back on the radar.
If long USD/JPY positions built around the old carry framework continue to unwind, the pair could still have room to fall further.
At the same time, the article flags a clear condition to watch: unless USD/JPY can quickly recover back above 155, the market may begin to treat former support as new resistance. That would be a meaningful change, though not automatically a full trend reversal.
The bigger question is whether policy architecture is changing
In the end, the article says many of the forces behind the yen’s recent move still rest on expectations that have not yet been fully tested. Those include the prospect of faster BOJ action, a reduced reflation bias in Japanese policy, possible GPIF repatriation flows, Washington’s preference for a stronger yen, and a Federal Reserve that has not truly shifted to a more hawkish stance.
That is why the third break of 155 deserves attention.
But the larger question is whether the market has merely kicked open a stubborn technical door, or whether Japan is starting to change the policy framework on the other side of it. In foreign exchange, the article argues, those are two very different trades.