European Central Bank research links the US equity rally to Magnificent Seven concentration, strong earnings expectations and multi-year low equity risk premia

The European Central Bank published Economic Bulletin research assessing why US equity prices have risen sharply since early 2023, with valuations elevated most visibly in the so-called Magnificent Seven. The analysis compares the current AI-driven upswing with the dot-com period and concludes that market concentration, optimistic earnings expectations and compressed equity risk premia have been central to the resilience of US equities despite tighter monetary policy. At current prices, Alphabet, Amazon, Apple, Meta, Microsoft, Nvidia and Tesla represent around one-third of S&P 500 market capitalisation, up from one-fifth five years ago, and trade at a forward price-to-earnings ratio of around 30 versus an S&P 500 median of 20 and a long-term median of 17. Unlike the late-1990s boom in smaller, more leveraged firms, the ECB points to the large technology firms’ higher profit margins of around 20%, ample cash reserves and cheap access to financing, alongside barriers to entry such as fixed costs and first-mover advantages. Analysts’ expectations of double-digit earnings growth for the S&P 500 in 2025 and 2026 are presented as unusually strong in historical terms and dependent on uncertain realised AI-related productivity gains, while dividend discount model results suggest risk appetite has also been a key driver, with equity risk premia at multi-year lows, particularly for the information technology sector. The ECB concludes that elevated valuations and high concentration leave equities exposed to adverse shocks, including the potential for risk-off shifts and greater sensitivity to negative macroeconomic revisions when valuations are high.