The European Central Bank published research in its Financial Stability Review finding that stretched valuations in technology and artificial intelligence related equities, especially in the United States, have created a key financial stability vulnerability for the euro area. Euro area investors have significant exposures to these markets, with investment funds at the centre, and the analysis shows that recent inflows into US equities were driven mainly by US macroeconomic expectations linked to the AI boom. The article notes that euro area holdings of all equities have doubled over the past decade, while holdings of US equities have quadrupled. The investment fund sector is the largest euro area holder of both equities overall and US stocks in particular. ECB calculations indicate that about 70% of the increase in euro area holdings of US equities between 2015 and 2025 reflected valuation effects, with the remaining 30% coming from net transactions. A BVAR model suggests US macroeconomic factors were the main driver of euro area fund inflows into US equities in recent years, while weaker global risk sentiment increasingly weighed on flows and US monetary easing since late 2024 provided additional support. Flows into US technology funds also react more strongly than flows into broader US or euro area equity funds to macroeconomic, monetary policy and risk shocks, leaving them more exposed to sudden reversals. The ECB warns that if AI adoption, productivity gains or expected profits disappoint, or if geopolitical conditions worsen, outflows could force asset sales and amplify market stress, with spillovers to euro area corporate funding conditions and to household wealth through rising direct and indirect ownership of fund shares.