Will Anthropic's first day of public trading occur before OpenAI's first day of public trading? Resolves NO if OpenAI lists first, both list simultaneously, or neither lists by December 31, 2027.

probability: 93%

rationale:

Anthropic holds a commanding and observable lead in the IPO process. On October 26, 2026, the company publicly filed its Form S-1 to list on the Nasdaq under "ANT" sec.gov. Under SEC rules, an issuer using the confidential review process must file publicly at least 15 days before launching its roadshow 2 sources. This makes November 10 the earliest possible start for formal marketing, aligning closely with reports that Anthropic is targeting a Thanksgiving-week debut fortune.com. Base rates for large IPOs strongly favor a near-term listing: of 22 large US IPOs from 2019 to 2026, the median time from public filing to pricing was 27.5 days, with the vast majority pricing within two months.

In contrast, OpenAI's path to a public listing is decidedly longer. While the company confidentially submitted a draft S-1 in June 2026, a check of EDGAR filings confirms no public S-1 has been filed as of October 26 2 sources. Leadership has actively managed expectations away from a near-term debut; CEO Sam Altman explicitly ruled out a 2026 listing, calling it "an ill-advised moment to go public" 3 sources. Furthermore, OpenAI has been pursuing a massive $30 billion private funding round 2 sources. Securing this capital would bridge its balance sheet and significantly reduce any immediate pressure to enter the public markets, reinforcing CFO Sarah Friar's guidance of a 2027 IPO finance.yahoo.com.

Given these timelines, the probability of Anthropic listing first is exceptionally high. For this outcome to not occur, OpenAI must overtake Anthropic, both must list on the exact same day, or neither can list by December 31, 2027. The first two scenarios are highly improbable due to structural SEC registration constraints and the stark divergence in current management intent. An OpenAI overtake would require Anthropic to suffer a prolonged delay while OpenAI executes an abrupt reversal in strategy, publicly files, and completes the mandated waiting and roadshow periods.

The primary risk to Anthropic listing first is that market volatility, valuation pushback, or AI-specific headwinds force Anthropic to pull its offering entirely, resulting in neither company listing before the end of 2027. Recent market conditions have been uneven, with some infrastructure issuers delaying or pausing their offerings 2 sources. However, Anthropic's immense and immediate capital needs—driven by projected computing commitments—create a strong incentive to press ahead despite volatility 2 sources. Even if Anthropic's timeline slips from late 2026 into early 2027, it retains a mature public filing and could relaunch quickly once conditions stabilize, preserving its decisive structural advantage.