The launch of Kimi K3 stole the spotlight last week, but Anthropic took it back when its Fable 5 model disproved a math conjecture that had stood for 87 years.
Anthropic researcher Levent Alpoge announced on X on Sunday that Fable 5 had produced a counterexample to the Jacobian conjecture, a central open problem in algebraic geometry posed in 1939, thanking the model for “working during the World Cup final.”
The counterexample is just 216 characters long, and New Scientist reports it was simple enough to verify that many mathematicians have already done so.
Queen Mary University of London mathematician Abhishek Saha called it “a pretty big deal,” saying it is likely the biggest conjecture AI has helped settle to date.
China’s Frontier Labs Are Racing for Second
The discovery capped a brutal week in AI. Chinese startup Moonshot AI released its 2.8-trillion-parameter Kimi K3 model on Thursday, which briefly rattled U.S. chip stocks and crushed its domestic rivals: shares of Zhipu and MiniMax both plunged on the news.
Demand was so hot that Moonshot paused new signups within two days, a compute squeeze analysts say may ultimately benefit Nvidia Corporation (NASDAQ:NVDA) and Micron Technology Inc. (NASDAQ:MU).
Then on Sunday, Alibaba Group Holding (NYSE:BABA) previewed its flagship Qwen3.8 Max, describing it as “second only” to Anthropic’s Fable 5. Notably, Alibaba published no benchmarks or independent tests to support the claim. Alibaba shares still rose as much as 5.4% Monday.
On Polymarket, traders give Alibaba a 79% chance of having the best Chinese AI model at the end of July, ahead of Moonshot at around 16%.
But Traders Say the Real Race Isn’t Close
Globally, those same traders see one leader. Anthropic trades near 99% to have the best AI model at the end of July on more than $7 million in volume, with Moonshot and Alibaba each priced below 1%. On the year-end horizon, Anthropic sits at 65%, with Google second at 13%. Moonshot is the top Chinese company, at 3%.
Anthropic may not stay private much longer. The company reportedly filed a confidential S-1 in June after a $65 billion round at a $965 billion valuation, and Polymarket traders give a listing 64% odds by year-end.
Until then, backers Amazon.com Inc. (NASDAQ:AMZN) and Alphabet Inc. (NASDAQ:GOOGL) may be the closest public proxies.
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