South Korea just handed its retail traders a turbocharger. The country launched its first single-stock 2x leveraged ETFs on May 27, tied to chipmaking giants Samsung Electronics and SK Hynix, and Goldman Sachs is already waving a yellow flag.

The investment bank warns that the new products could amplify both market concentration and volatility in a market where those two stocks already account for nearly 50% of the entire Kospi index.

The numbers behind the nervousness

Goldman Sachs projects that the 14 new leveraged ETF products could attract net inflows of roughly 5.3 trillion won, or approximately $3.5 billion. That is a serious pile of capital pointed at a very narrow slice of the market.

Rebalancing activity from leveraged products has already accounted for up to 60% of SK Hynix’s trading volume on volatile days. On the most chaotic trading sessions, the majority of volume in one of Korea’s most important stocks was driven not by fundamental investors but by the mechanical buying and selling that leveraged ETFs require to maintain their daily exposure targets.