The market is pricing in an 84% probability of a rate hike by the Bank of Japan in September.
Position holders on the Polymarket platform have sharply revised their expectations regarding Japan's monetary policy. In just two weeks, the probability of a rate hike by the Bank of Japan at the September meeting has surged from 22% to 84%. This is a signal that no trader working with Asian markets or yen pairs can afford to ignore.
The reason for this reversal is the apparent loss of effectiveness of currency interventions by Japanese authorities. Recent coordinated actions by the regulator, aimed at supporting the national currency, have ceased to have the desired impact. The yen has not only given up a significant portion of its gains but is also posting its worst weekly performance in three months.
Interventions no longer work
This week, the yen has fallen by approximately 1%, reaching 159.43 per dollar. This is the worst weekly result since May. Notably, the currency has already retraced about half of the rally that followed the joint intervention by the Bank of Japan in late July and early August. Before those measures, the exchange rate held around 164 yen per dollar.
History repeats itself: after the April intervention, the yen slid back to 40-year lows in the following months. It seems the market has stopped viewing one-off injections as a long-term support factor. Tokyo's former top currency diplomat Mitsuhiro Furusawa rightly notes that authorities can deploy reserves at any time, but the key signal for the market is a willingness to tighten policy more quickly, not one-off measures.
Betting on the central bank's resolve
Market participants, according to Polymarket data, are now betting on a quarter-point rate hike. OCBC strategist Sim Moh Siong emphasizes that intervention alone is insufficient to reverse the yen's trend. "It's no surprise that the yen has given up ground again," he comments, adding that the currency needs clear support from the Bank of Japan, which is ready to tighten monetary policy.
Inflation in Japan is approaching the target level, creating a favorable backdrop for rate normalization. However, the opposite scenario carries serious risks: if the regulator leaves rates unchanged, the market reaction will be immediate and painful. The yen has already fallen to 160 per dollar once after similar disappointments. Now the market is waiting not for new interventions, but for concrete steps from the central bank.
My view: The market, as usual, is pricing in the most "hawkish" scenario, and the 84% probability looks overstated. The Bank of Japan is historically cautious and may prefer to pause to assess the sustainability of inflation. If the regulator fails to meet expectations, we will see a sharp yen pullback and heightened volatility across all Asian markets. Traders should prepare for any scenario and not overestimate current quotes from prediction platforms.