OpenAI pitches investors on ChatGPT rebound as $100 billion funding round nears close

Sam Altman has a message for OpenAI employees and investors: ChatGPT's growth slump is over.

The OpenAI chief told staff on Friday that the company's flagship chatbot is "back to exceeding 10% monthly growth," according to an internal Slack message viewed by CNBC.

The announcement comes as OpenAI rushes to close what could become a $100 billion fundraising round, with private meetings already underway to pitch the company's momentum to prospective backers.

More than 800 million people use ChatGPT weekly, but the product has faced mounting pressure from rivals. Google continues to dominate search, while Anthropic's Claude has steadily eaten into OpenAI's territory, particularly among developers.

The competitive squeeze prompted OpenAI to declare a "code red" in December, temporarily shelving other projects to focus on improving ChatGPT.

Now Altman and CFO Sarah Friar are selling investors on a turnaround story, highlighting consumer strength, a growing enterprise business and superior access to computing resources, according to a person familiar with the pitch who requested anonymity due to confidentiality.

Codex surges as OpenAI battles Anthropic for developer mindshare

OpenAI's most dramatic gains have come from Codex, its coding assistant. Altman told employees the product grew roughly 50% in a single week following the launch of a new model, GPT-5.3-Codex, and a standalone app for Apple computers.

"This was a great week," Altman wrote in Friday's message, calling Codex's trajectory "insane."

The growth carries strategic weight. Codex competes directly with Anthropic's Claude Code, which has seen widespread adoption over the past year. OpenAI has been circulating internal data showing Codex gaining market share from Claude Code, according to a screenshot seen by CNBC.

The rivalry spilt into public view during Super Bowl weekend, when Anthropic ran ads mocking OpenAI's decision to introduce advertising within ChatGPT. Altman fired back on X, calling the commercials "deceptive" and insisting OpenAI would "obviously never run ads in the way Anthropic depicts them."

Advertising rollout begins despite controversy

OpenAI will officially begin testing ads within ChatGPT on Monday, according to a person familiar with the matter. The company has said the ads will be clearly labelled, appear at the bottom of responses and will not influence the chatbot's answers.

Long term, OpenAI expects ads to generate less than half its revenue, the person said. The move puts the company in direct competition with Google and Meta, which have dominated digital advertising for years, along with Amazon, which has become a major player more recently.

Altman also said OpenAI plans to launch "an updated Chat model" this week, though he provided no additional details.

Funding talks intensify with Microsoft, Nvidia and Amazon in the mix

OpenAI expects fundraising discussions to accelerate over the next two weeks, one person said. The round could close in two stages, as CNBC previously reported. Microsoft, Nvidia and Amazon are in talks for the first tranche, with Amazon considering an investment of up to $50 billion. SoftBank, which contributed $30 billion to OpenAI's $41 billion round in March, has discussed putting in another $30 billion in a second closing.

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The structure and terms remain fluid and could still change before the deal finalises.

For now, Altman's message to both employees and investors is clear: OpenAI weathered a difficult period and emerged with renewed momentum. Whether that pitch is enough to command a valuation approaching $400 billion remains to be seen.