Five ECB economists argued in an August 17, 2026 ECB Blog post that US CAPE valuations are near their historical peak and a correction 'is likely,' with the euro area exposed despite its small tech sector. We use that post only as a starting point -- not reproducing its text or conclusions -- and independently test its framework against our own real-yield data and this programme's companion research. We find the rational-option-value-versus-speculative-excess distinction (Pastor & Veronesi 2009; Scheinkman 2014; Hong & Stein 2007) analytically sound, and identify the discount-rate channel as the critical, underexamined link: US 10Y real yields rose from 2.35% to 2.44% in a single week around the July 2026 FOMC decision. A correction driven by rising real yields would look mechanically different from one driven by monetization disappointment, and could occur even if AI's productivity promise is fully validated. We do not conclude AI equities are or aren't a bubble -- we conclude the question is under-specified without first distinguishing which mechanism is doing the work.
24 August 2026