Citi: 10% Drop in Topix Index Could Trigger Sharp USD/JPY Decline

A deep correction in Japanese equities could trigger a sharp decline in the USD/JPY currency pair, but the market would need to fall considerably before sustained yen appreciation emerges, according to strategists at Citi.

Correction Threshold for Yen Strength

The recent record-setting rally in Japanese stocks has been accompanied by portfolio rebalancing and currency-hedging transactions that have amplified the yen's weakness. While the Nikkei 225 has pulled back from its highs, Citi notes that the broader Topix index remains elevated near 4,000.

Analysts suggest a more significant market downturn is required to reverse the trend. Historically, the yen has tended to strengthen more rapidly when the Topix declines by over 10%. Based on this pattern, a key level to watch is 3,600 on the index.

A move toward this level could prompt overseas investors to reduce their currency hedges or unwind positions tied to Japanese equities, creating significant buying pressure for the yen and pushing USD/JPY lower.

The Stock-Currency Interplay

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The relationship between Japanese stocks and the USD/JPY is complex and bidirectional. A weaker yen supports Japanese exporters by increasing the value of their overseas earnings, which can boost stock prices. In turn, a rising equity market generates investment flows that often place further downward pressure on the currency.

This connection has become more visible amid elevated stock-market volatility, with equity gains exerting stronger downward pressure on the yen. The current adjustment from record highs has so far been insufficient to generate a meaningful move toward yen appreciation.

Shifting Sensitivity and Outlook

However, the sensitivity of USD/JPY to movements in Japanese stocks has declined since 2025, according to Citi. This shift is partly attributed to the narrowing monetary-policy gap between the United States and Japan, which has provided underlying support for the yen.

To illustrate this change, Citi's analysis shows that based on the correlation since 2025, the implied level for USD/JPY is around 160. Applying the stronger correlation observed between 2012 and 2024 would produce an estimate closer to 175. While Citi's base case remains bullish for Japanese equities, suggesting USD/JPY could remain elevated, this reduced sensitivity may limit further currency weakness driven by stock market gains.