SpaceX's $2.1T Valuation May Hinder Future Returns, Historical Data Suggests

SpaceX (SPCX-US), now the sixth-largest U.S. public company at $2.1 trillion market cap, faces headwinds common to mega-cap stocks: historical underperformance versus broader markets. Research Affiliates data shows a hypothetical portfolio of the world's 10 largest companies underperformed global equities by 1.8 percentage points annually from 1980 to 2020. The trend persists in 2026. As of June 12, the top 10 U.S. stocks by market cap declined 0.3% year-to-date, lagging the S&P 500's 8.5% gain. The current mega-cap cohort—including Nvidia (NVDA-US), Apple (AAPL-US), Alphabet (GOOGL-US), Microsoft (MSFT-US), and Amazon (AMZN-US)—trades at an average trailing P/E of 68.4x versus 25.1x for the S&P 500, per LSEG data. Research Affiliates founder Robert Arnott notes SpaceX ranks 520th in the firm's fundamental index (weighted by book value, revenue, and cash flow rather than market cap), with just 0.0036% allocation—reflecting concerns about valuation-driven outperformance sustainability.