The market is pricing in an 84% probability of a rate hike by the Bank of Japan in September.
The derivatives market and prediction platforms have radically revised expectations regarding the Bank of Japan's monetary policy. Just two weeks ago, traders estimated the chances of a key rate hike in September at only 22%, but now that figure has jumped to 84%. Such a sharp reversal in sentiment is a direct consequence of the weakening effect of the Japanese authorities' currency interventions.
The yen loses its hard-won ground
This week, the yen weakened by approximately 1%, reaching 159.43 per dollar. This is the worst weekly result since May. The currency has already given back about half of the gains that followed the coordinated currency intervention in late July and early August. At that time, the exchange rate bounced off the 164-per-dollar level, but now the upward momentum has faded.
The historical context only heightens concern: after the April intervention, the yen slid back to a 40-year low over the following months. This demonstrates the limited effectiveness of one-off measures without support from fundamental monetary policy.
Notably, even Tokyo's former top currency diplomat, Mitsuhiro Furusawa, acknowledged the possibility of using currency reserves again at any moment. However, he emphasized that the authorities are also prepared to signal to the market a faster pace of policy tightening — and this is precisely what is now the key driver.
Betting on the central bank's resolve
The link between interventions and key rate decisions is becoming increasingly evident. Polymarket participants now estimate the probability of a quarter-point rate hike at above 80%. The market appears to have concluded that one-off currency measures cannot reverse the yen's dynamics, and a more decisive step from the Bank of Japan is needed.
OCBC strategist Sim Moh Siong notes that the yen's weakening was expected, and that monetary policy tightening is required for sustainable support of the currency. This view aligns with growing expectations of accelerated rate hikes, especially as inflation approaches the target level.
The opposite scenario carries risks: if the regulator leaves the rate unchanged, the market could react with sharp disappointment. The yen has already fallen to 160 per dollar after similar decisions. Market participants are now betting on the central bank's actions rather than on new interventions.
My view: The market is likely right in its assessment — the Bank of Japan is backed into a corner. Interventions without a rate hike merely postpone the problem, and the regulator will have to choose between defending the currency and risking destabilization of the bond market. The September meeting will be a key test of the new central bank leadership's resolve.