The Bank of Korea (BOK) warned Sunday that single-stock leveraged exchange-traded funds (ETFs) tied to Samsung Electronics and SK hynix could amplify market volatility, joining growing regulatory concerns over the high-risk products. The rare warning is expected to add momentum to financial authorities' efforts to tighten investment requirements for the products. In a written response to Rep. Park Sung-hoon of the main opposition People Power Party, the BOK said leveraged ETFs tracking Samsung Electronics and SK hynix could exacerbate the market's heavy concentration in the two major chipmakers, which account for more than half of the Korean stock market by market capitalization and trading value. "The domestic stock market has become increasingly concentrated in a handful of semiconductor stocks amid improving earnings in the sector," the BOK said. "Single-stock leveraged ETFs could further intensify one-way trading as investors pour money into or pull out of the products in response to changes in market expectations or the business environment." The central bank warned that a sharp decl