According to @EricBalchunas, US-focused ETFs account for $11 trillion out of $18 trillion in global ETF assets, and US equities have outperformed EFA by 185 percentage points over the past decade (source: Eric Balchunas, X, Sep 15, 2025). Balchunas credited a note from Athanasios Psarofagis in highlighting this US equity leadership and ETF asset concentration (source: Eric Balchunas, X, Sep 15, 2025). For equity traders, this supports closely monitoring the SPY versus EFA relative strength trend and maintaining a US-overweight bias in momentum strategies if the trend persists (source: Eric Balchunas, X, Sep 15, 2025). For crypto traders, stronger US equity leadership can matter because stock–crypto correlations have risen since 2020, with BTC and ETH increasingly trading as risk assets alongside equities (source: International Monetary Fund, “Crypto Prices Move More in Sync With Stocks, Posing New Risks,” Jan 2022).