OpenAI told investors its annualized revenue for September was almost $50 billion, a drop from what it signaled earlier, a person familiar with the matter told Reuters on Thursday. The company had previously indicated at a separate event that last month's revenue run rate was approaching $70 billion.

The discrepancy mainly arose from an attempt to produce a direct comparison with rival Anthropic's figures, the source said. Unlike Anthropic, OpenAI excludes sales via cloud partners such as AWS and Google Cloud from its headline number — and Anthropic pays cloud partners about 16% of every dollar earned through them.

Both companies are preparing to go public, a process that will give Wall Street a clearer view of their finances. OpenAI started the year at $20 billion in annualized revenue versus $6 billion in 2024, but Anthropic's annualized revenue crossed $65 billion in July and is reportedly set to reach $100 billion by year-end.

On Friday, Bloomberg reported the company is now telling investors it expects to reach or exceed $70 billion in annualized revenue by the end of the year, driven largely by enterprise growth -- up from about $50 billion at the end of September. The figures were shared in discussions for a fundraising round said to target $30 billion or more at a $1.4 trillion valuation. The revenue news briefly weighed on tech shares Thursday, with the Nasdaq 100 falling 1.4%.