The Year of the Mega IPO: What Investors Should Know

SpaceX, Anthropic, and OpenAI are preparing initial public offerings in 2026, with SpaceX targeting a June 12 debut at a $1.75 trillion valuation, according to a Wealthfront analysis [1]. Anthropic and OpenAI have made confidential filings with the U.S. Securities and Exchange Commission, though neither has confirmed a listing date [1]. SpaceX plans to sell roughly $80 billion in stock, implying a free float of only 4.57% [1]. Anthropic, a San Francisco-based artificial intelligence company founded in 2021 by former OpenAI employees, carried an estimated private value of $965 billion as of May 2026 [7]. OpenAI’s private valuation sits near $1 trillion [1]. None of the three firms is profitable, though Anthropic is reportedly on track for its first profitable quarter [1]. Venture capital investors have long fueled such companies through private funding rounds, seeking returns via an eventual initial public offering or acquisition [4]. Privately held firms valued above $1 billion are known as unicorns; as of May 2024, 1,248 existed globally [4]. The transition to public markets for firms of this scale has drawn comparisons to earlier tech listings. Google’s 2004 IPO came after rapid growth and product expansion, while Facebook’s 2012 offering was among the largest in tech history [3][5]. Index providers have adjusted rules in anticipation of low-float mega-listings. The Nasdaq-100 Index introduced a Fast Entry pathway for new listings ranking within the top 40 constituents by full market capitalization, evaluating them on their seventh trading day [1]. A separate capping mechanism limits the initial weight of securities with floats up to 33 1/3%, basing weight on available shares rather than full market cap [1]. The Center for Research in Security Prices relaxed a rule that required at least 10% free float for a large IPO; a stock is now eligible if its free-float market capitalization equals at least 0.005% of the total free-float capitalization of all index-eligible stocks [1]. Under the Nasdaq-100 framework, SpaceX’s $80 billion float would be multiplied by three, yielding a $240 billion basis for index weighting — slightly below Shopify’s market cap and far below the weight implied by the full $1.75 trillion valuation [1]. The CRSP US Total Market Index, which is free-float weighted, would base SpaceX’s weight on the $80 billion float, placing it near UPS at roughly 0.12% of the index [1]. S&P confirmed its eligibility rules will not change, maintaining a 10% float minimum, positive trailing earnings, and a twelve-month seasoning requirement [1]. SpaceX’s lockup provisions allow varying percentages of locked-up stock to be sold after the first and second public earnings releases, as well as at milestone dates from 70 to 180 days after the IPO, which will gradually increase its free float and index weight [1]. Wealthfront noted that its direct indexing strategies will purchase newly eligible stocks using cash from deposits, dividends, or tax-loss harvesting, without realizing gains in other holdings [1].