During Thursday's (October 8) Asian trading session, the US dollar edged slightly lower against the Japanese yen, trading below the 158 level. Japan's August wage growth came in faster than expected, yet the yen weakened rather than strengthened after the data release, with USD/JPY pulling back from above 158.50 to around 158.00, returning to where it stood before the figures were published.

Wage Data: Headline Beat, Soft Details

Nominal wages rose 3.8% year-on-year, above the 3.7% expectation but below July's level. Real wage growth slowed to 1.5%, marking a second consecutive month of deceleration. The key lies in the revision: July's figure was revised down from 4.7% to 4.3%, a downward adjustment of 0.4 percentage points, four times the size of the headline beat of 0.1 percentage points. This revision significantly diminishes the significance of the headline surprise, indicating that the previous strong reading was overstated and that the actual trend in wage momentum is weaker than the initial figure suggested.

Yen Reaction: Spike and Retreat, Dollar Side Dominates

USD/JPY briefly spiked above 158.50 after the data release, the highest since September 25, before falling back to around 158.00, completing a full round trip. This price action sends a clear signal: the wage data failed to provide sustained support for the yen. Slowing real wages, a sharp downward revision to July, and no pull-forward in the timing of the Bank of Japan's next rate hike kept the yen under pressure under rate differential logic. For most of October, USD/JPY will primarily follow drivers on the dollar side.

Fiscal and Policy: Tax Cut Pledges and the Undervaluation Argument

Japanese Prime Minister Sanae Takaichi said in parliament on Tuesday that she would cut the consumption tax on food without issuing new debt. The 10-year Japanese government bond yield held near 3.11% on Wednesday, close to a three-decade high. Yields driven higher by budget concerns rather than rate expectations tend to weaken rather than bolster a currency. Finance Minister Kato Ayako and US Treasury Secretary Bessent described the yen as undervalued at the end of September. Wednesday's release of the Federal Reserve meeting minutes documented a foreign exchange intervention operation conducted by the New York Fed on behalf of the Treasury, namely the joint yen-buying operation with Japan on July 31, when USD/JPY was slightly below 164.00. "Undervalued" is the language used by both finance ministries for a currency on which they have already spent money once.

Rate Differentials and Hike Probabilities: A 25bp BOJ Hike Is Just a Drop in the Bucket

After the Bank of Japan's September 18 rate hike, the policy rate stands at 1.25%, while the Federal Reserve's is at 3.75%-4.00%. Futures markets assign roughly a 71% probability to another BOJ move before December. The Fed's October 28 meeting and the BOJ's October 30 meeting carry the same probability of a hike, both close to 17%. A 25 basis point BOJ hike would only narrow one-tenth of the rate differential gap. Friday's University of Michigan survey will release US household one-year inflation expectations, which stood at 4.6% last month. A higher reading would increase Fed rate hike bets and push USD/JPY higher in tandem.

Summary

Japan's August wage data presented a "headline beat, soft details" combination: nominal wages at 3.8% exceeded expectations, but a sharp downward revision to July and a second consecutive month of slowing real wages undermined the substantive significance of the data. The yen's spike and retreat showed that rate hike expectations were not pulled forward and the dollar side dominated the exchange rate. On the fiscal front, tax cut pledges and elevated government bond yields constitute mixed signals, while both finance ministries' remarks on yen undervaluation and the record of joint intervention in July indicate rising policy-level attention to the exchange rate. The rate differential gap remains enormous, and a single BOJ hike can only narrow one-tenth of it. In the short term, USD/JPY will continue to follow dollar movements, with Friday's Michigan inflation expectations as the next point to watch. At 08:25 Beijing time, USD/JPY was quoted at 157.87/88.