OpenAI’s Codex surges 50% while ChatGPT hits 10% monthly growth as Sam Altman signals comeback amid Anthropic rivalry and potential $100B fundraise

After months of pressure from rivals and growing doubts across Silicon Valley, CEO Sam Altman told employees that ChatGPT has “back to exceeding 10% monthly growth.” The message posted on Slack late last week signaled that OpenAI believes the slide has stopped and momentum is returning, according to CNBC.

The timing matters. More than 800 million people now use ChatGPT each week, yet competition has tightened. Google continues to push its AI products deeper into search and productivity tools. Anthropic has gained real traction with developers, especially through Claude Code. Inside OpenAI, the response was blunt. A “code red” declared in December led teams to pause side projects and refocus on product performance.

That bet appears to be paying off, at least in the short term.

Altman said OpenAI’s coding product, Codex, grew about 50% in the past week. The figure stands out in a market where developer loyalty can shift quickly. Codex now goes head-to-head with Anthropic’s Claude Code, which had enjoyed a strong adoption wave across the past year.

OpenAI released a new Codex model, GPT-5.3-Codex, last week. A stand-alone app for Apple computers followed soon after. Altman described the growth as “insane” in the internal message. “This was a great week,” he wrote.

The week was far from quiet.

Tensions spilled into public view after Anthropic aired Super Bowl ads mocking OpenAI’s decision to introduce advertising in ChatGPT. Altman responded on X, calling the ads “deceptive” and saying OpenAI would “obviously never run ads in the way Anthropic depicts them.”

“I guess it’s on brand for Anthropic doublespeak to use a deceptive ad to critique theoretical deceptive ads that aren’t real, but a Super Bowl ad is not where I would expect it,” Altman said in a post on X.

Inside OpenAI’s Comeback Push: Rapid Codex Growth, New ChatGPT Model, and a $100B Fundraise

Behind the scenes, OpenAI is moving forward anyway. The company is set to begin testing ads inside ChatGPT, according to a person familiar with the plan. The ads will sit at the bottom of responses, carry clear labels, and stay separate from how answers are generated. OpenAI expects advertising to account for less than half of revenue over time, as it enters a market long dominated by Google and Meta, with Amazon gaining ground.

The push for revenue runs in parallel with a massive fundraising effort.

Altman and CFO Sarah Friar have been meeting privately with investors to sell OpenAI’s growth story. The pitch centers on consumer scale, enterprise adoption, and access to compute. Internal charts shared during the discussions show Codex gaining share against Claude Code, based on OpenAI data.

“Altman and CFO Sarah Friar have been selling investors on OpenAI’s growth story as the company looks to wrap up what could be a $100 billion fundraising round,” CNBC reported, citing sources familiar with the matter.

The funding round under discussion could reach $100 billion. Talks are expected to intensify over the next two weeks. OpenAI closed a $41 billion round in March, anchored by a $30 billion commitment from SoftBank. The new round may close in stages, starting with capital from Microsoft, Nvidia, and Amazon. SoftBank has discussed adding another $30 billion.

Nothing is final. The structure remains fluid.

What is clear is the message Altman wants employees, investors, and rivals to hear. OpenAI sees its products stabilizing. Growth has resumed. The company plans to keep pushing, even as the race tightens and the stakes climb.