The market is pricing in an 84% probability of a rate hike by the Bank of Japan in September.
Participants in the decentralized prediction market Polymarket have sharply revised their expectations regarding the Bank of Japan's monetary policy. In just two weeks, the probability of a key rate hike at the September meeting soared from 22% to an impressive 84%. This signals a radical shift in sentiment among traders and investors.
The intervention effect is weakening
The key trigger for this reversal was the weakening effect of currency interventions by Japanese authorities. The yen came under pressure again: this week, the exchange rate fell by about 1%, reaching 159.43 per dollar. This is the worst weekly result since May. The currency has already lost about half of the gains that followed the coordinated intervention by the Bank of Japan in late July and early August, when the rate pulled back from the 164-per-dollar level.
The historical context here is extremely telling. After the April intervention, the yen slid back to a 40-year low in the following months, demonstrating the limited effectiveness of one-off measures without a change in fundamental policy. Tokyo's former top currency diplomat Mitsuhiro Furusawa recently noted that authorities could deploy currency reserves at any time and are also ready to signal a faster rate hike to support the national currency.
Players are betting on a rate hike
It is precisely this link between interventions and key rate decisions that explains the sharp change in expectations. The market no longer believes in the effectiveness of targeted currency measures and is now betting on decisive action from the regulator. OCBC strategist Sim Moh Siong rightly notes that interventions alone will not reverse the dynamics of the Japanese currency—the yen needs clear support from the Bank of Japan, which is ready to tighten monetary policy. This view fully aligns with growing expectations of a faster rate hike, especially as inflation approaches the target level.
The opposite scenario carries significant risks. If the regulator leaves the rate unchanged, the market will quickly react with disappointment, and the yen could slide back to the 160-per-dollar level. Market participants are now counting on central bank steps rather than new currency interventions, making the upcoming meeting one of the most important events for the Japanese economy this year.
My expert assessment: The prediction market typically responds very sensitively to real signals, and such a sharp jump in probability from 22% to 84% is not just a speculative move but a reflection of a fundamental shift in the perception of BOJ policy. If the rate is indeed raised in September, it will become a powerful signal for global markets and could trigger yen appreciation, putting pressure on Japan's export sector and, indirectly, on risk appetite for assets, including cryptocurrencies.