FT News Briefing covers the AI sector's "existential crisis" as tech stocks fall following calls from Sam Altman and Dario Amodei to slow development, with FT columnist John Foley analyzing the market and IPO implications. The episode also examines a US supply chain squeeze driven by tariffs, energy costs, and AI demand, while noting that foreign investors are shifting from Treasuries to stocks as the 10-year yield hits 5%. Finally, FT Beijing bureau chief Joe Le discusses new Chinese exit bans aimed at retaining skilled workers and protecting intellectual property amid intensifying tech co…