The yen’s status as a haven in times of global stress faces growing skepticism, threatening to exacerbate a selloff that sent the currency to an eight-month low this week.

For decades, investors have turned to the yen during market shocks, from financial crises to geopolitical blowups. The logic was simple: Japan’s huge current-account surplus, stable political system and deep domestic investor base made it a reliable refuge when risk assets tumbled.

But that instinct is now under strain, undermined by the Japanese currency’s increasingly inconsistent behavior as a hedge and a move toward gold as part of a trade that shuns major currencies. The yen broke above the key level of ¥150 against the dollar this week following hard-line conservative Sanae Takaichi’s surprise victory in Japan’s ruling party leadership race.