Anthropic’s confidential S-1 filing on June 1, 2026, followed by its targeting of a September or October listing, has anchored trader consensus that it will reach public markets ahead of OpenAI. The company’s $65 billion Series H round at a $965 billion valuation and banker discussions with Morgan Stanley, Goldman Sachs, and JPMorgan underscore its accelerated timeline. In contrast, OpenAI filed days later but has since signaled a potential shift toward 2027, with reports citing internal deliberations and a desire to complete additional milestones as a private entity. These developments have produced the current 87.5% market-implied odds for Anthropic, reflecting capital-weighted assessment of filing order, regulatory review pace, and management statements on preferred windows. Key upcoming catalysts include any public S-1 amendments or final pricing announcements that could alter the relative timelines.