The three largest initial public offerings (IPOs) in history could occur in 2026. SpaceX is targeting a June listing of $75 billion in stock at a $2 trillion valuation. OpenAI and Anthropic could also have IPOs later in 2026 with estimated valuations of $1 trillion each. Due to their enormous size, these three companies would be entering the public markets as mega cap stocks, where index ownership is typically 35 to 45% of shares outstanding.
Some major index providers are considering rule changes to allow fast entry for these companies into the major indices. For example, S&P is reportedly considering waiving the current 12-month listing and 4 quarters of positive earnings requirements for SpaceX. Fast entry into indices such as the Nasdaq 100 or S&P 500 could create a supply-demand imbalance where there are too many index funds required to buy and not enough shares of these low-float new issues. Harvard researchers found that IPOs fast tracked into the CRSP indices raised 6% more capital than their non-fast-tracked counterparts.1. This effect could be even larger for an IPO with fast entry into the S&P 500 or Nasdaq 100.
For investors, the arrival of these companies into public markets is an unusual event. Unlike the other mega cap companies in the S&P 500, the wealth creation from these new market entrants has occurred so far in private markets, meaning that most investors did not participate.
Investors and their managers should be aware of the uncommon dynamics at play in equity benchmarks, while remaining hopeful that these offerings prove mutually beneficial with companies gaining access to deep pools of capital, and investors gaining an opportunity to participate in the long-term growth of transformative technology.
- Chris Murray, Marco Sammon, Primary Capital Market Transactions and Index Funds, The Review of Asset Pricing Studies, 2026;, raaf013,https://doi.org/10.1093/rapstu/raaf013