Anthropic's confidential S-1 filing on June 1, 2026, followed by a $65 billion Series H round at a $965 billion valuation, has positioned it ahead in the IPO race, with reports pointing to a potential listing as early as September or October 2026 using major underwriters like Morgan Stanley and Goldman Sachs. OpenAI filed its own confidential S-1 one week later at a comparable scale but has since signaled a shift toward a 2027 debut amid internal deliberations on timing and private-company priorities. These recent filings and timeline signals have driven trader consensus, as Anthropic's accelerated path through regulatory review creates a clear first-mover edge in the competitive large language model landscape. Key catalysts ahead include any public S-1 releases or earnings updates that could confirm or delay these windows.