Samsung Electronics shares tumbled on Tuesday, falling 13.39% to 220,000 won on the Korea Exchange. The drop wiped 34,000 won off the stock in a single session and marked the company’s worst one-day fall in nearly two decades.

The selloff came as investors reacted to growing fears about stronger Chinese competition in memory chips, one of Samsung’s most important businesses. Concerns about that competitive pressure appeared to hit sentiment sharply and turned Samsung into the center of the day’s market weakness.

The decline did not stay limited to one stock. The broader South Korean market also posted significant losses as Samsung’s slide added to pressure across local equities.

The scale of the move highlights how sensitive investors remain to changes in the memory chip industry and to signs that Chinese rivals could challenge established players more aggressively. For Samsung, Tuesday’s trading stood out as one of its most severe market setbacks in years.