The market is pricing in an 84% probability of a rate hike by the Bank of Japan in September — what this means for the yen
Participants on the decentralized prediction platform Polymarket now estimate the probability of the Bank of Japan raising its key interest rate at the September meeting at 84%. Just two weeks ago, this figure stood at only 22% — such a sharp reversal in expectations deserves close attention.
This dramatic shift in assessments came after the currency intervention by Japanese authorities stopped supporting the yen. The national currency has lost a significant portion of its recent gains and is now posting its worst weekly performance in three months.
The Intervention Effect Is Fading
This week, the yen has declined by approximately 1% — to 159.43 per dollar. This is the worst weekly result since May. The currency has already given back about half of the strengthening observed after the coordinated intervention by the Bank of Japan in late July and early August. Before those measures, the exchange rate was hovering near 164 per dollar.
A similar picture emerged earlier: after the April intervention, the yen approached a 40-year low again in the following months. This confirms that one-off injections without changes to fundamental monetary policy provide only a temporary effect.
Traders Are Betting on a Rate Hike
The link between interventions and key rate decisions explains the shift in market expectations. Traders on Polymarket estimate the probability of a quarter-point rate hike at above 80%. Such a consensus looks logical: inflation in Japan is approaching the target level, and authorities, judging by signals, are ready to tighten policy to support the currency.
Significantly, even former senior currency diplomats in Tokyo do not rule out the renewed use of reserves at any moment. However, in my assessment, the market is currently betting specifically on central bank steps, not on new interventions. The reversal in expectations on Polymarket is a clear indicator that investors see a rate hike as the only sustainable way to stabilize the yen.
The opposite scenario — keeping the rate unchanged — carries significant risks. After such decisions, the yen has already fallen to 160 per dollar, and market disappointment could trigger a new wave of weakening. Under current conditions, central bank inertia will be perceived as weakness, which will only increase pressure on the national currency.
My professional view: the 84% probability looks overstated, but the direction of expectations is correct. The Bank of Japan has found itself in a trap — delaying policy tightening will cost it market trust, while a hasty decision without convincing inflation data could hurt the economy. The optimal compromise appears to be a rate hike in September with cautious rhetoric about further steps.