Anthropic + OpenAI vs Microsoft - higher valuation on December 31?

Resolution Criteria

This market will resolve to "OpenAI + Anthropic" if the combined private market valuation of Anthropic and OpenAI is larger than Microsoft's market capitalization on December 31, 2026, or to "Microsoft" if Microsoft's market capitalization exceeds that combined valuation. NPM Prices are published for trading days only and are updated once daily at 1:00 PM ET on the following calendar day. If NPM has not published relevant data for the specified date by 1:00 PM ET on January 1, 2027, this market may remain open until 11:59 PM ET on January 4, 2027. If no further data is released by that time, the market will resolve according to the data available. If NPM ceases publishing relevant data prior to the specified date, this market will resolve based on the NPM data published prior to the cessation of coverage, as well as applicable public market capitalization data following an IPO or direct listing. If a private company completes an IPO or direct listing prior to the specified date, this market will resolve according to the company's public market capitalization at the market close of the specified date or the most recent trading day. Public market capitalization will be determined using the final official regular-hour trading price published for the company's primary listed common equity on its primary exchange for the specified date or the most recent trading day, multiplied by the company's total outstanding common shares at the relevant time. If the listed company merges with or acquires another entity and remains the parent company, no change to resolution methodology applies. If a listed company is acquired, merges into another entity and is no longer the surviving parent company, or otherwise ceases to exist as an independent entity prior to the end of the period, only the last NPM valuation and applicable public market capitalization achieved prior to completion of the transaction will be considered for resolution. No transaction, acquisition, or merger consideration will be considered for resolution. The resolution source for this market is NPM data published here (https://fe.secondmarket.com/companies/company-30839e0b-2730-4495-839f-1bf638fa9cca/data?return_url=https://polymarket.com/finance/privates) and here (https://fe.secondmarket.com/companies/company-3e197763-4ff8-4d8c-bd1f-cc2792937757/data?return_url=https://polymarket.com/finance/privates). The resolution source for any period following an IPO, direct listing, or relevant corporate action, will be official exchange trading data and publicly reported share counts. If Anthropic and OpenAI's combined valuation is equal to Microsoft's public market capitalization at resolution, this market will resolve to 50-50. Revisions to previously published NPM data made after their initial release will not be considered, unless made to correct clearly erroneous data.

This market asks whether the combined private market valuation of Anthropic and OpenAI will exceed Microsoft's public market capitalisation on 31 December 2026. Trading volume is heavily concentrated on Microsoft as the higher-valued entity. Resolution is determined by NPM private-market data for the two AI firms against Microsoft's official exchange capitalisation at the close of 31 December 2026.

Market structure

The market has two outcomes: 'Anthropic + OpenAI' or 'Microsoft.' Current volume is overwhelmingly concentrated on Microsoft. Resolution compares the sum of NPM-published private valuations for Anthropic and OpenAI against Microsoft's public market capitalisation on 31 December 2026. A fallback window extends to 11:59 PM ET on 4 January 2027 if NPM data is delayed. An exact tie resolves 50-50.

Background

Microsoft is one of the world's largest publicly traded companies by market capitalisation, consistently ranking among the top two or three globally. OpenAI, in which Microsoft holds a significant stake, has attracted private funding rounds that placed its valuation among the highest ever achieved by a private technology company. Anthropic, backed by major investors including Alphabet and Amazon, has similarly reached a valuation in the tens of billions of dollars through successive fundraising rounds. The question of whether these two AI-focused private companies, combined, could rival or surpass one of the most valuable corporations in history reflects the scale of capital flowing into generative AI — but also the substantial gap that currently exists between private valuations and the mature public market capitalisation of established technology giants.

Key factors

Microsoft's public market capitalisation fluctuates daily with equity markets and is sensitive to earnings results, macroeconomic conditions, interest rate changes, and investor sentiment toward its Azure cloud and AI integration strategy. OpenAI's and Anthropic's NPM valuations are updated less frequently and reflect secondary market transactions rather than continuous price discovery, meaning they may not respond to news as quickly. A formal IPO or direct listing by either company before 31 December 2026 would shift their valuation to public market methodology, introducing real-time price discovery. New funding rounds at either company could reset NPM-reported valuations upward. Conversely, if either company faces regulatory setbacks, competitive pressure, or funding difficulty, NPM valuations could stagnate or decline. Microsoft's capitalisation could also shift substantially in either direction over a multi-month period, particularly given broad market movements in the technology sector.

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