The yen’s weakness is turning foreign investors away from Japanese stocks.

The Nikkei 225 Stock Average has jumped 14% this year, outperforming its global peers. But for dollar-based investors, the gains shrink to just above 3% after the yen’s tumble to a 34-year low against the greenback. That’s far below the S&P 500’s increase of 9.5% and the Hang Seng Index’ dollar-based returns of 11%.

"Investing in Japanese equities becomes harder if the currency continues to weaken," Yue Bamba, head of Japan active investments at BlackRock, said in an interview in Tokyo. "When you speak with global investors about Japan, FX is definitely top on the mind for everyone."