OpenAI Returns To The Ring As Anthropic’s Cheaper AI Raises The Stakes – Elon Musk Teases Grok 4.5

• In recent days, Anthropic restored access to its flagship Mythos and Fable AI models and launched Sonnet 5.
• SpaceXAI founder Elon Musk jumped in to say that his company would roll out its Grok 4.5 AI model available to the public on Wednesday.  
• OpenAI and Anthropic have filed confidentially for their IPOs, although OpenAI is reportedly delaying its IPO until next year.

OpenAI upped the heat on Wednesday, launching its flagship GPT-5.6 Sol AI model, weeks after Anthropic restored its powerful Mythos model and launched a low-cost Sonnet 5 AI model as both firms march ahead in their plans for initial public offerings.

OpenAI announced that its GPT-5.6 flagship model, Sol, as well as the lower tiers Terra and Luna, will launch this Thursday publicly, after delaying the release last month at the U.S. government's request amid mounting national security concerns that powerful AI systems could be misused.

Axios reported, citing a source, that the Donald Trump administration had approved a broad launch of GPT-5.6 following additional testing and meetings between ‌the company ⁠and government officials.

Last month, Anthropic had disabled its most advanced AI models — Mythos 5 and Fable 5 — for all users after the government's June 12 export control order. The curbs were lifted last week after Anthropic implemented certain safeguards.

On June 30, Anthropic released Claude Sonnet 5, an AI model that the company says delivers nearly the same performance as its flagship Opus 4.8 at mid-tier prices. 

The release showed the company is trying to make capabilities that were once limited to its most expensive models available to more users, while driving broader developer adoption ahead of its planned IPO.

Musk Says Grok 4.5 Launching On Wednesday

After OpenAI’s announcement, SpaceXAI founder Elon Musk jumped in to say that his company would roll out its Grok 4.5 AI model available to the public on Wednesday.  

Based on strong positive feedback from customers in our beta test program, @SpaceXAI will make Grok 4.5 available to the public tomorrow,” Musk said in an X post.

Taking a dig at Anthropic, he added: “It is an Opus-class model, but faster, more token-efficient and lower cost.”

Race To IPO

OpenAI and Anthropic are racing toward stock market listings and have recently submitted confidential filings to regulators, although OpenAI’s IPO timeline now appears to have shifted to a later date.

OpenAI now broadly trails Anthropic, based on the most recently disclosed numbers. In April, Anthropic said it tripled its annual revenue run rate to $30 billion, surpassing OpenAI’s ARR of about $24 billion. Anthropic is valued at $1.09 trillion, compared to OpenAI’s private market valuation of $867.9B, according to data from Nasdaq Private Market.

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