The yen approaches 160 again, UBS warns: After short-sellers are "washed out", the shorting window reopens

The yen remains under pressure, intervention risks are reigniting, and subtle shifts in market structure are setting the stage for a new wave of bearish attacks.

After the holiday break in Japan, the USD/JPY quickly surged above 158, just a step away from the 160 mark. Last Friday, the Bank of Japan raised interest rates by 25 basis points, but Governor Kazuo Ueda's subsequent comments failed to satisfy market expectations for further tightening. As a result, the yen weakened instead of strengthening, with a significant two-week cumulative decline.

Meanwhile, Japan’s 10-year government bond yield jumped 10 basis points on Thursday to 3.075%, hitting a new high since 1996. The global bond market selloff and mounting domestic fiscal pressures have resonated, further intensifying market volatility.

Key shift in hedge fund positions: According to the latest CFTC data, for the week ending September 15, hedge funds turned net long yen for the first time in seven months, holding around 251 billion yen (about $1.6 billion) in bullish positions on the yen. UBS strategists pointed out that speculative yen shorts have been “completely flushed out,” which has cleared the way for the market to rebuild bearish positions.

The core dilemma facing the market now is: uncertainty over the Bank of Japan’s rate-hiking trajectory, continued hawkish policy expectations from the Federal Reserve, and upward pressure on long-term rates due to Japan’s fiscal expansion. These three forces are jointly suppressing the yen, and the deterrent effect of intervention is gradually being digested by the market. Bets on a “strong yen” by Suzuki are about to undergo a real pressure test at the 160 mark.

Rate hikes fail to rescue the yen; the 160 threshold returns as the focus

At its September 18 policy meeting, the Bank of Japan decided to raise interest rates by 25 basis points, but this move failed to arrest the yen’s decline. Ueda’s post-meeting remarks were interpreted as dovish by the market, lacking clear guidance on further tightening, causing the yen to continue to weaken after the hike, while the USD/JPY briefly surged above 158.

It’s worth noting that the rate hike decision was not unanimous, with two committee members opposing it, and no one advocating for a 50 basis point rate increase.

Matthew Ryan, head of strategy at Ebury Partners, said, “If the market lacks confidence in further tightening from the Bank of Japan, the yen remains at risk of further short-term weakness. FX intervention is essentially a blunt instrument—without strong monetary policy support, Japanese authorities will find it hard to curb yen selling.”

Japanese bond yields soar to near 30-year highs, piling on domestic and external pressures

After the Japanese holiday, the market’s reopening was met with a shock. On Thursday, the 10-year Japanese government bond yield surged 10 basis points to 3.075%—its highest level since 1996. The five-year yield also rose 9.5 basis points to 2.37%, with the curve shifting up across the board.

External pressure comes from the US: strong economic data and a weakly received Treasury auction pushed US yields to near 20-year highs, with rising oil prices further reinforcing inflation expectations. Market pricing for continued Fed rate hikes is becoming increasingly aggressive.

On the domestic front, fiscal pressures are also hard to ignore. Reports indicate the Japanese government is considering raising mid-term defense spending targets to 3.5% of GDP, aligning with NATO and other US allies. This potential increase in spending has drawn heightened market scrutiny to Prime Minister Sanae Takaichi’s fiscal plans, putting notable pressure on long-dated government bonds.

Bearish “reset” complete; a new shorting window may have opened

CFTC position data reveals an intriguing shift in market structure: for the week ending September 15, hedge funds’ net position in the yen flipped from short to long for the first time since July 2025, with net longs totalling about 251 billion yen.

However, the UBS strategy team led by Shahab Jalinoos offered a sharply different interpretation—this isn’t a bullish signal but rather the result of a short squeeze. They noted that speculative yen shorts have been “completely cleared,” and with the carry trade environment still favorable and the US-Japan rate differential remaining wide, this actually sets the stage for investors to rebuild short positions.

In other words, the appearance of net longs may not mark the start of a yen reversal, but rather the prelude to a new shorting cycle. Carol Kong, FX strategist at Commonwealth Bank of Australia, said, “If US bond yields continue to rise and markets keep testing the resolve of Japanese authorities to defend the yen, USD/JPY could break through 160 very soon.”

Intervention threshold and Suzuki’s commitment: can coordinated action reoccur?

The symbolic significance of the 160 threshold goes far beyond technicals. Ray Attrill, head of FX strategy at National Australia Bank, commented, “It’s entirely possible we revisit 160, but I expect the mere threat of intervention will prevent the exchange rate from really breaking through this level.”

However, the lasting impact of intervention largely depends on whether Washington gets involved. Attrill noted that Japanese unilateral intervention, when monetary policy fundamentals are unfavorable, has historically not led to sustained reversals, and the market could quickly absorb the impact of another solo operation.

This summer, the US joined Japan in buying yen, significantly raising the risk cost for shorting the currency. Finance Minister Suzuki has repeatedly expressed public support for a stronger yen, effectively issuing a challenge to traders. If USD/JPY returns to 160, Suzuki’s credibility will be put directly to the test.

Attrill added that further US involvement in intervention may come with strings attached—Japan would need to show a willingness to raise rates faster and more aggressively than markets currently expect. Satsuki Katayama has previously confirmed that the framework for US-Japan joint intervention remains valid, but the actual tolerance level of the US Treasury and the trigger conditions for joint action remain the biggest unknowns in the market.

Analysis suggests that the effect of rate checks has already proven short-lived and limited, and market skepticism toward unilateral Japanese intervention is rising. Against this backdrop, option market pricing around intervention risk near the 160 mark is quietly shifting.

Carol Kong noted that a rapid USD/JPY breakout above 160 would “substantially increase the likelihood of official action,” particularly given recent precedents for rate checks and the historical norm of coordinated intervention. A swift break above 160 could trigger a repricing of risk reversal in the options market, amplifying fx volatility.