Yen Tumbles 0.84% as Dollar Recovers Ahead of US CPI; Short Positions Unwind Sharply
The Japanese yen fell 0.84% to 159.14 per dollar on August 10, 2026, its steepest daily decline in nearly five months, while the US dollar index rose 0.20% to 99.80, according to Reuters. The moves came as traders positioned ahead of the next US CPI release, with the dollar index trading near a two-month trough despite the session's bounce.
The sell-off in the yen was not driven by fresh positioning alone. Commodity Futures Trading Commission data for the week to August 4, 2026 showed net short positions in the yen plunged by $8.865 billion to $3.604 billion, the largest reduction in the period covered, as reported by CNBC. That unwind of bearish yen bets preceded the August 10 drop, suggesting that the remaining market was less crowded short and therefore less vulnerable to a squeeze, which may have amplified the yen's downside when the dollar found its footing.
The broader context here is one of a dollar that has been grinding lower through mid-2026 even as US inflation data has sent mixed signals. The dollar index at 99.80 remains depressed by historical standards, and the yen's slide to 159.14 puts the pair back in territory that has historically attracted intervention attention from Japanese authorities. The positioning data, however, tells a more nuanced story: with net shorts having been cut so aggressively, the fuel for a sustained yen rebound has been partly spent.
US inflation data has been the dominant driver of dollar direction this year. The January 2026 CPI report showed headline prices up just 0.2% on the month, with core CPI (excluding food and energy) rising 0.3% and advancing 2.5% year-on-year, its smallest annual gain in nearly five years, per Reuters. That benign reading stood in sharp contrast to the May 2026 print, when inflation rose more than expected with CPI up 3.8% year-on-year, leading markets to price out Federal Reserve rate cuts entirely. By June, forecasts had moved further: economists anticipated a 0.5% monthly increase and a 4.2% year-on-year jump, which would have been the largest annual rise since April 2023, according to Reuters.
The trajectory matters for the yen specifically because the Bank of Japan's ultra-loose policy stance leaves the currency acutely sensitive to US rate expectations. When US inflation runs hot and Fed cut expectations retreat, the US-Japan rate differential widens in the dollar's favour. When inflation cools and cut odds rise, the yen catches a bid. The August 10 price action, with the dollar rising and the yen falling, is consistent with markets either pricing in firmer US CPI or hedging against that outcome.
Elsewhere in Asia, the Monetary Authority of Singapore has held its policy stance steady. In its Monetary Policy Statement of January 29, 2026, MAS stated it would maintain the prevailing rate of appreciation of the S$NEER and projected core inflation to normalise in 2026, averaging 1.0–2.0%, per MAS. The S$NEER, MAS' intermediate policy target and a trade-weighted basket of currencies, stood at 141.39 on May 1, 2026, having drifted down from 141.62 on April 10, according to MAS exchange rate data. The mild easing of the index within the policy band is consistent with a maintained appreciation slope rather than any policy shift.
Bloomberg's 2026 investment outlook, published in January, flagged the possibility of dollar weakness early in the year followed by a second-half rebound, while noting that European currencies could lose ground as rate cuts take hold, as reported by Bloomberg. The dollar's August 10 bounce to 99.80, coming off a two-month trough, is consistent with the later stages of that thesis, though a single session's move does not confirm a trend reversal.
For market participants, the immediate question is whether the next US CPI print validates the recent dollar recovery or extends the yen's reprieve. The positioning adjustment has already happened on the short side; what remains is the macroeconomic catalyst. Until that data lands, the yen at 159 is trading on positioning mechanics rather than a clear directional view.
