OpenAI's revenue is indeed growing, but not as fast as some reports had suggested.

According to people familiar with the matter, OpenAI recently told investors that its annualized revenue was close to $50 billion as of the end of September. That figure is roughly $20 billion lower than revenue numbers previously disclosed in other reports, including those from The Information.

The sources said OpenAI did not deny the revenue figures in those earlier reports. The previously reported data came from an estimate by an anonymous investor; at the time, OpenAI Chief Financial Officer Sarah Friel said the company's revenue run rate increased by 70% between the end of June and the end of September.

OpenAI itself has not publicly disclosed that growth rate, but media outlets including Bloomberg and The Information reported on it based on that figure. People with knowledge of the actual numbers said the early estimates included revenue OpenAI received from Microsoft's sales of OpenAI technology to Azure cloud customers.

After the two companies updated their commercial agreement, OpenAI stopped receiving that portion of revenue around April. Annualized revenue is generally calculated by multiplying monthly revenue by 12, but companies do not use uniform standards for what they include.

For example, Anthropic's revenue accounting includes all sales revenue generated by partners such as Amazon Web Services, Microsoft (NASDAQ: MSFT) and Google reselling its Claude models. In the past, when OpenAI calculated revenue, it included the 20% of total revenue it had to share with Microsoft (NASDAQ: MSFT), and it also included the 20% share belonging to OpenAI from revenue generated by Microsoft (NASDAQ: MSFT) Azure platform sales of OpenAI models.

But starting in April this year, OpenAI no longer shares in revenue generated by Microsoft (NASDAQ: MSFT) selling OpenAI models to Azure cloud customers. Before the two companies launch their respective IPOs, they will likely need to align their revenue accounting standards. Anthropic plans to go public later this year, while OpenAI may move forward with a listing next year.