US and South Korean memory and chipmaker stocks, long outperformers, have sharply reversed; many major names are in bear market, down over 20% from recent highs as of Wednesday close. Reasons: Samsung reported record profit and stronger guidance but shares were sold off as investors fretted that AI infrastructure spending may be excessive. Geopolitical risk rose after Trump suspended a US‑Iran memorandum, adding anxiety around AI trades; if conflict persists and inflation worries return, AI‑exposed stocks could see further downside. Sector rotation also pressures the group: with hyperscalers’ returns lagging chipmakers, strategists including Morgan Stanley CIO Mike Wilson had forecast a chip pullback and now expect funds to flow back into hyperscalers, which look relatively cheap as chip stocks near prior highs.(金十数据)