PremiumAI-related stocks tumbled at the end of last week on a second 'DeepSeek moment', as the latest Chinese open-weight AI model (Mooshot AI's Kimi K3) reminded investors that cheap, light alternatives are snapping at the heels of the state-of-the-art proprietary models."This Is Concerning": Why Everyone Is Freaking Out About China's Kimi K3 Model 1. Open-what? A new twist on age-old format wars