The yen’s slide rattled shares of some non-Japanese exporters in Asia on Monday, with South Korean car makers hit particularly hard on worries that rivals in Japan will gain a pricing edge in global markets.

The yen plummeted in value Friday and continued to drop Monday, after the Bank of Japan unexpectedly announced additional stimulus measures in an effort to lift inflation. A weaker yen makes Japanese products more competitive in overseas markets. The yen was at ¥113.89 per dollar midday Monday in New York, around a seven-year low and sharply weaker than ¥109.22 on Thursday before the Bank of Japan announcement.

In Seoul, shares of auto makers Hyundai Motor and Kia Motors fell 5.9% and 5.6%, respectively, on Monday.

South Korean and Japanese companies often compete head-to-head in the same product groups in global markets, notably cars and electronics goods.

From the Bank of Japan’s standpoint, “you’re giving your industry a head start relative to someone else’s,” said Markus Rosgen, regional head of equity strategy at Citi in Hong Kong. “The perception in the equity market will be that they [South Korea] will have to take a hit from the lack of competitiveness versus the Japanese.”