BOJ Rate Check Sparks Sharp Yen Surge

The yen strengthened significantly against the dollar on September 18 after the Bank of Japan conducted a rate check, a move commonly taken in preparation for possible intervention in the foreign exchange market.

The sharp increase began around 11:30 p.m. Japan time and reached more than 1 yen within an hour, briefly touching the upper 156 yen range against the dollar.

Earlier that day, the Bank of Japan raised interest rates for the first time in about 31 years, but this initial decision was met with a weaker yen, trading between 157-158 yen against the dollar.