Forget the Fed. The Bank of Japan could deliver next week’s market shock.

While much of Wall Street remains focused on U.S. monetary policy, the Bank of Japan's upcoming meeting may prove the more consequential event for global markets. The BOJ has spent years as an outlier among major central banks, maintaining ultra-loose policy even as peers raised rates. Any signal that this stance is shifting—whether through yield-curve control adjustments or forward guidance—could ripple across asset classes.

The mechanism matters for U.S. investors because the yen has long served as a funding currency for carry trades, in which investors borrow cheaply in Japan and deploy capital into higher-yielding assets abroad, including American equities. A meaningful change in Japanese policy could strengthen the yen and prompt unwinding of those positions, pressuring risk assets globally.

What to watch: the BOJ's language on inflation sustainability and any tweaks to bond-purchase operations. Even without a formal rate change, a hawkish surprise could move currency and bond markets quickly. For long-term investors, the takeaway is that policy divergence between Tokyo and Washington remains a live source of volatility—not just a background story.