Why it's rumored
PiunikaWeb reported Grok 4.3 beta appearing in the SuperGrok Heavy model picker without an x.ai/news announcement; xAI had not published a model card or API pricing at the time of the first sightings.
What to expect
Stealth beta for SuperGrok Heavy with native video input, document generation (slides, PDF, spreadsheets), and a larger checkpoint Musk described as still training after the initial 500B-parameter beta.
Timeline
April 17, 2026
Grok 4.3 beta spotted
PiunikaWeb reports Grok 4.3 beta rolling out quietly to SuperGrok Heavy on web and mobile.