Foreign investors were net sellers on Korea's stock markets this month, the country's bourse operator said Sunday, while remaining net buyers of exchange-traded funds (ETFs) amid heightened market volatility. Foreigners offloaded a net 12.1 trillion won ($8.12 billion) on the main bourse and 338.1 billion won on the tech-heavy secondary market through Thursday this month, according to the Korea Exchange (KRX). The KRX said foreigners were net sellers on the main bourse in eight of the 12 trading sessions through last week. The market was closed Friday for Constitution Day. In contrast, foreigners scooped up 593.7 billion won worth of ETFs this month, posting net purchases in 10 of the 12 trading sessions. The most popular ETF among foreign investors was KODEX Leverage, which tracks twice the daily performance of the benchmark Korea Composite Stock Price Index (KOSPI), with net purchases of 195 billion won, followed by KODEX 200, another ETF tracking the main index, with 180.6 billion won. Meanwhile, foreigners were net sellers of single-stock leveraged ETFs, offloading 79 billion won wort