Micron Surges 12.2%, Chip Stocks Rally on July 21 Amid China AI Model Debate

According to MarketWatch, memory and chip stocks surged on Tuesday (July 21), with Micron Technology jumping 12.2%, SanDisk rising 14.4%, and SK Hynix ADR climbing 13.8%. Western Digital gained 12.5% and Seagate Technology advanced 11.1%. The Philadelphia Semiconductor Index rose 5.2%, marking its best single-day performance in weeks.

The rally came as investors reassess the threat posed by China's open-source AI models, particularly Moonshot AI's Kimi K3. Bank of America analyst Vivek Arya noted that despite China's models' efficiency improvements, they still require comparable or greater memory capacity as model parameters scale. He emphasized that open-source models force customers to independently configure hardware and memory infrastructure, contrasting with closed-source alternatives, and that such competition supports positive outlooks for memory chipmakers.