The Bank of Korea called for stronger monitoring of overseas derivatives tied to Korean chipmakers, warning their rapid growth risks amplifying domestic market swings as it cited leveraged bets by hedge fund Situational Awareness as a driver of recent volatility.

The South Korean market’s concentration in semiconductor stocks, foreign investors’ portfolio rebalancing and the buildup and unwinding of domestic leverage acted as drivers of the unprecedented volatility witnessed in Kospi from January to July, the central bank said in its semiannual Monetary Policy Report to parliament Thursday.