The market is pricing in an 84% probability of a rate hike by the Bank of Japan in September: what is happening with the yen
Participants on the decentralized prediction platform Polymarket have sharply revised their expectations regarding Japan's monetary policy. In just two weeks, the probability of the Bank of Japan raising its key interest rate in September has surged from 22% to 84%. This is a signal that neither Forex traders nor cryptocurrency investors can afford to ignore.
The reason for this reversal is a noticeable weakening of the effect from Japanese authorities' currency interventions. The yen, which had previously shown steady gains, is now under pressure again. This week, the USD/JPY exchange rate fell by approximately 1%, reaching 159.43 yen per dollar. This is the worst weekly performance in the last three months.
The yen has given back half of its gains
After coordinated currency interventions in late July and early August, when the exchange rate hovered around 164 yen per dollar, the Japanese currency strengthened, but has now lost roughly half of that gain. A similar scenario was already observed in April: after the intervention, the yen returned to its lows within a few months. This confirms that one-off measures without changes in fundamental policy cannot alter the trend.
Notably, Tokyo's former top currency diplomat Mitsuhiro Furusawa recently emphasized in an interview that authorities are ready to deploy currency reserves at any moment. However, he also made it clear that the market should expect more decisive signals from the Bank of Japan—in particular, an acceleration in the pace of rate hikes. It is this signal, rather than another intervention, that could prove decisive for the yen.
Betting on central bank action
The market appears to have heard this message. OCBC strategists agree that interventions alone will not reverse the dynamics of the Japanese currency. "It's no surprise that the yen has given up ground again," they note, pointing to the need for clear support from monetary authorities. Given that inflation in Japan is approaching the target level, expectations of faster policy tightening look justified.
However, the opposite scenario carries significant risks. If the Bank of Japan leaves the rate unchanged, the market will quickly react with disappointment—and the yen could fall back to 160 per dollar. Currently, market participants are betting on central bank steps rather than new interventions.
My analysis: The sharp jump in probability on Polymarket is not mere speculation but a reflection of a real shift in institutional players' expectations. For the crypto market, this is an important macroeconomic factor: yen strengthening and Bank of Japan policy tightening could trigger an unwinding of carry trades, which traditionally amplifies volatility in risk assets, including bitcoin. Keep an eye on the September meeting—it could become a trigger for global capital flows.