Investors weigh OpenAI IPO prospects and Microsoft's 27% stake

By Splitfeed EditorialLast updated Oct 3, 2026, 05:20 UTC

In late September and early October 2026, financial outlets began examining the IPO prospects of the two most prominent private AI companies. Anthropic was cited at a $2 trillion valuation as speculation about a public offering grew, a figure that prompted direct comparisons to the so-called Magnificent 7 technology giants. OpenAI was referenced at a $1.4 trillion valuation, with analysts and investors treating a listing as a matter of when rather than whether. Running alongside both stories was a specific investment thesis: Microsoft holds approximately 27% of OpenAI, and some investors are buying Microsoft shares now as a proxy way to capture gains from any eventual OpenAI listing, on the argument that the stake represents value not yet reflected in Microsoft's share price.

The numbers involved are large enough to reshape the broader technology investment landscape if either company actually lists. Anthropic at $2 trillion would place it above most established technology firms by market capitalisation, a valuation that raises genuine questions about what revenue and profit trajectory could justify it. OpenAI at $1.4 trillion carries similar scrutiny. The Microsoft angle adds a layer of complexity: a 27% stake in a private company with no guaranteed listing timeline is an unusual asset for a publicly traded corporation to hold, and how that stake would be valued, taxed, or distributed in a real IPO scenario remains an open and contested question.

With no published reactions from the Pro-AI, Anti-AI, or Middle Ground camps on this specific story, it is possible to sketch what each would typically argue. The Pro-AI camp would likely treat these valuations as confirmation that the market recognises transformative long-term value in frontier AI, and would point to investor enthusiasm as rational rather than speculative. The Anti-AI camp would be expected to question whether companies with high compute costs and uncertain profit margins can sustain trillion-dollar valuations, drawing comparisons to previous technology bubbles. The Middle Ground camp would probably focus on the structural uncertainties, including governance changes at OpenAI, regulatory risk, and the untested mechanics of how Microsoft's stake would function in a public offering, as reasons for measured rather than exuberant assessment.

The clearest signals to watch are any formal IPO filing from either OpenAI or Anthropic, a revised valuation round that either confirms or deflates the current figures, and any disclosure from Microsoft about how it intends to account for or eventually realise its stake. Those events would give investors and analysts concrete terms to argue about rather than projections.