The market is betting on a rate hike by the Bank of Japan: the probability has reached 84%.
Participants on the decentralized prediction platform Polymarket have dramatically 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 an impressive 84%.
Why the yen is weakening again
The key trigger for this shift in sentiment has been the fading effect of currency interventions by Japanese authorities. The yen, which had previously shown steady gains, is now rapidly losing ground. This week, the Japanese currency fell by approximately 1%, reaching 159.43 yen per dollar—its worst weekly performance since May of this year.
Notably, the yen has already given back about half of the gains it made following the coordinated currency intervention by the Bank of Japan in late July and early August. Before those measures, the exchange rate had been hovering around 164 yen per dollar. A similar pattern was observed earlier: after the April intervention, the yen returned to its multi-year lows in the following months.
Market view: interventions are not a panacea
Strategists I spoke with agree that one-off interventions cannot fundamentally change the dynamics of the Japanese currency. The yen needs clear and consistent support from monetary authorities—namely, a willingness to tighten monetary policy. Inflation in Japan is gradually approaching the target level, creating favorable conditions for a rate hike.
The opposite scenario carries significant risks. If the regulator leaves the rate unchanged, the market could react with sharp disappointment. There have already been precedents where the yen collapsed to 160 per dollar after such decisions. Market participants are now betting on central bank actions rather than new currency interventions.
My analysis: The sharp jump in probability on Polymarket reflects not just speculative sentiment, but a fundamental shift in how the Bank of Japan's policy is perceived. The market is tired of temporary measures and demands decisive action. However, it is worth remembering that a high probability in forecasts does not guarantee the event—and if the regulator fails to meet expectations, volatility in the currency market could be extreme.