Top stories today:

1. Elon’s xAI launches Grok 4, Grok 4 Heavy AI models
2. OpenAI said to release AI-powered web browser to rival Google Chrome
3. Apple said to ready 1st upgrade for struggling Vision Pro headset
4. X CEO Linda Yaccarino quits after stabilizing ads
5. Perplexity launches AI-powered web browser Comet

0. Data and calendar

Listen to our AI-generated podcast summarizing today’s newsletter (beware of hallucinations):

1. Elon’s xAI launches Grok 4, Grok 4 Heavy AI models to counter OpenAI, Anthropic, Google

Grok 4 has topped the Artificial Analysis Intelligence Index, surpassing OpenAI’s o3-pro and Google’s Gemini 2.5 Pro:

• Hit an all-time high score of 88% in GPQA Diamond, surpassing Gemini 2.5 Pro’s previous record of 84%.

• All-time high score in Humanity’s Last Exam of 25%, beating Gemini 2.5 Pro’s 21% record.

• Trained on xAI’s Colossus supercomputer.

• Grok 4 Code specialized version for coding.

Grok 4’s pricing is equivalent to Grok 3 at $3/$15 per 1M input/output tokens, identical to Claude 4 Sonnet

• More expensive than Gemini 2.5 Pro ($1.25/$10 for <200K input tokens) and o3 ($2/$8).

Grok 4 has recorded slightly higher output token usage compared to peer models

Grok 4 Heavy is xAI’s “multi-agent version”, offering even higher performance than Grok 4

• SuperGrok Heavy has also been launched as xAI’s most expensive subscription plan at $300/month to offer an early preview to Grok 4 Heavy.

• The release follows Grok’s antisemitism row and Yaccarino’s departure.

• Relatedly, Elon Musk broke his silence on Grok’s Nazi bender and said it was “was too compliant to user prompts… That is being addressed.”

3. OpenAI said to release AI-powered web browser to rival Google Chrome