Why the Yen Stayed Weak After Japan’s Rate Hike—and Why ¥160 Matters

Japan’s September rate hike did not eliminate the main reason investors could still favor dollars over yen: U.S. interest rates remained much higher. The widely expected BOJ decision also left traders weighing how quickly further tightening might follow. Tokyo’s three-day Silver Week market closure added a period in which currencies moved while Japanese stocks and bonds were shut. 231218

Why a rate hike did not lift the yen

On September 18, the Bank of Japan raised its policy rate from 1% to 1.25%, its highest level in 31 years. The increase was widely expected, and the board approved it by a 7–2 vote. Reuters reported that the yen weakened after the decision as traders interpreted the two dissenting votes as a reason to doubt the pace of future hikes. 23

The U.S. policy-rate range was still 3.75%–4.00%, according to a September 22 market analysis—a gap of roughly 2.5 to 2.75 percentage points over Japan’s new rate. That difference helps explain the appeal of carry trades, in which investors borrow lower-yielding yen to buy higher-yielding assets. It does not guarantee a weaker yen: a sharp currency reversal can quickly overwhelm the interest earned. 1217

What Silver Week changed—and what it did not

Tokyo’s stock and futures exchanges and the Japanese government bond market were closed from September 21 through September 23, with trading scheduled to resume September 24. Foreign-exchange trading continued. Thin holiday trading can make currency moves more pronounced, while Japanese shares and bonds have to absorb developments when their markets reopen. The closure may have amplified volatility; it does not, by itself, explain the yen’s underlying weakness. 1819

The ¥158 timing needs care. Sources report that dollar–yen reached about ¥158 around the September 18 BOJ decision, but a September 23 market report quoted ¥157.46. The available reporting therefore does not firmly establish that the yen crossed ¥158 on September 23, rather than on another day or at another point in trading. 101219

Why traders are watching ¥160

Japan’s earlier yen-buying and reports of a September 18 rate check keep renewed official action in view. A rate check can precede intervention, but it is not intervention itself. Nor do the cited reports establish ¥160 as an automatic trigger: the speed and disorderliness of a move could matter as much as the quoted level. 31418

If the yen keeps falling when Tokyo reopens, exporters could benefit from a weaker currency while import costs become a concern. If warnings or intervention instead produce a sudden yen rally, investors funding positions in yen could unwind carry trades; Reuters documented that risk during an earlier yen surge. Japanese government bonds face competing possibilities: expectations of more BOJ tightening could push yields up and prices down, while a broader retreat from risk could support demand for bonds. These are possible market responses, not predictions of the September 24 open. 21718