Dario's letter has been read by 73 million people, but the market only understands two words: slow down. So on Monday, AI supply chain blood flowed like a river NVDA -3.4%｜AMD -4.3%｜MU -5.2% AVGO -4.7%｜TSM -3.4% VST -5.2%｜GEV -8.6% On Saturday, September 12th, the CEO of Anthropic released "We Must Pace the Frontier," advocating for a "slower pace" in the AI industry. Sam Altman followed up the next day: 'Agreed with Dario, we need to pace the front.'. Elon Musk's three words: "Dario is right It is rare for the CEOs of three cutting-edge laboratories to stand on the same side, and this matter itself is worthy of vigilance. And - China calls this spreading fear, Trump says' whoever wins AI wins the world '. When one side slows down and the other is at full speed, the side that slows down loses. No one believes their opponent will stop, so no one will stop. The hidden stream that should be paid attention to: OpenAI and Anthropic are the most expensive laboratories that can afford compliance, and open-source models are rapidly catching up. Slow down=check=cost, this is a threshold that top players can afford but open source players cannot. Trump's former AI czar put it even more bluntly: it's not security, it's regulatory capture. Key fact: The total capital expenditure of the four major cloud factories in 2026 is about $700B, and their quarterly reports continue to be revised upwards. As long as no one announces a cut in CapEx, this wave is panic, not a fundamental collapse. The real focus should not be on Dario's letter, but on the next CapEx guidance for MSFT/GOOGL/META/AMZN. That's the thermometer of foam. CapEx guidance is "capital expenditure estimation", in plain language: a company tells investors how much money it expects to spend on equipment, building factories, or building data centers in the next quarter or year. This is a future investment plan, not an amount that has already been spent.