Taiwan Semiconductor Manufacturing Co. (TSMC) signage on the floor of the New York Stock Exchange (NYSE) in New York, US, on Friday, Jan. 2, 2026. Michael Nagle | Bloomberg | Getty Images As South Korea's and Taiwan's benchmark indexes surged to record highs this year — powered by Asia's trillion-dollar titans — it has raised concerns that their rallies are becoming dangerously dependent on a handful of artificial intelligence winners. South Korea's Kospi index has surged more than 80% this year, hitting one fresh high after another, while Taiwan's Taiex has also repeatedly posted new records as investors piled into the semiconductor trade at the center of the AI boom. "In a word, it's the AI hardware theme that's clearly what is propelling things," Goldman Sachs strategist Tim Moe told CNBC. Taiwan is "well over 80%" exposed to AI-related revenue streams while South Korea stands around 60%, he said, as soaring demand for memory chips and advanced semiconductors fuels an unprecedented earnings boom.…