The Japanese yen’s dramatic slide to its weakest levels in decades is not just a local phenomenon—it ripples through global markets and may be setting the stage for a fresh leg in the U.S. equity bull run. With trade flows, multinational supply chains and capital patterns shifting under the weight of a weak yen and a strong dollar, U.S. investors should pay attention: what happens in Tokyo can quickly echo on Wall Street. This article takes you through the mechanics of yen weakness, the intervention debate, and why that matters for key U.S. sectors such as semiconductors, autos and export-driven tech.

The evolution of the JPY/USD currency pair from 1 May 2025

The chart of real effective exchange rates shows the sharp decline of the yen in the recent period. The cause is mainly due to a clash of central bank policies. The US Fed continues to keep interest rates higher due to inflation (although there have already been two cuts this year), while the Bank of Japan maintains an extremely…