AI Rivals Duel: OpenAI, Anthropic Host Parties on Same Night

On May 5, 2026, OpenAI extended a substantial perk to over 8,000 developers who applied for its exclusive GPT-5.5 event: a tenfold increase in Codex rate limits on their personal ChatGPT accounts, effective immediately and continuing through June 5. This move, announced via email and telegraphed by CEO Sam Altman, aims to foster deeper engagement and encourage subscription upgrades.

This generous access period arrives as Anthropic has emerged as a dominant force, surpassing OpenAI in global LLM revenue market share for Q1 2026. Anthropic achieved 31.4% market share compared to OpenAI's 29%, but notably, extracts approximately seven times more revenue per user.

The intensifying rivalry was palpable in San Francisco, where both OpenAI and Anthropic hosted invite-only developer events on the evening of May 5. OpenAI's "GPT-5.5 on 5/5" gathering featured Sam Altman and the GPT-5.5 team, while Anthropic held a "Media VIP Welcome Reception" preceding its Code with Claude developer conference.

This competition extends to enterprise adoption, with Anthropic capturing a larger share of enterprise LLM spend. Anthropic's annualized revenue has reportedly topped $30 billion, with projections suggesting a potential valuation exceeding $900 billion in a new funding round, significantly outpacing OpenAI's current valuation of $852 billion.