Ex-Stability AI Research Lead Edwin Arbus Joins Anthropic

Edwin Arbus, former research lead at Stability AI, announced on X around September 1 that he has officially joined Anthropic, celebrating with a photo of his first-day morning run and the caption noting that this morning's run felt different. Peers and friends congratulated him in replies and reposts, making this the latest example of ongoing talent movement in the AI industry.

Confirmed

• Edwin Arbus himself (@edwinarbus) announced joining Anthropic; the news was relayed by multiple accounts including @lennysan, @altryne, @chongdashu, @trq212, @davidhoang, @abaaron and @sashadem
• @lennysan reported that he joined Anthropic as an engineer
• He shared a photo of his morning run on his first day as a celebratory post and interacted with friends in the comments
• Former Microsoft employee Michael Mazur (@mhmazur) reposted congratulations; user @bookwormengr joked with a waffle photo about "running while eating waffles" to salute the intense work pace

Unconfirmed

• Some reposts spell his name differently (Edwin Arbuisson, Edwin Arbuthnott, Edwino Arbosa); the spelling on his own account @edwinarbus is authoritative
• @mhmazur described him as a "former Microsoft executive," inconsistent with the "former Stability AI research lead" description elsewhere; his Microsoft tenure cannot be verified from the material
• His specific research direction at Anthropic is not disclosed

Why it matters

• As a former Stability AI research lead, Edwin was a core-level member of the Stable Diffusion team
• Stability AI has seen multiple core researchers depart since 2024 (e.g., Emad Mostaque stepping down as CEO); this move continues that trend
• Anthropic continues to absorb well-known AI researchers, showing the talent-gathering effect of top labs is still strengthening

2026-09-01 ~ 2026-09-02 · 10 related posts

• [source] Former Stability AI Research Lead Edwin Joins Anthropic — edwinarbus · 2026-09-01
• Edwin Arbus joins Anthropic — altryne · 2026-09-01
• [source] Edwin joins Anthropic as engineer — lennysan · 2026-09-01
• [source] Edwin Arbus announces he has joined Anthropic — chongdashu · 2026-09-02
• Edwin Arbuthnott joins Anthropic — a_baaron · 2026-09-02
• Edwino Arbosa joins Anthropic — sashadem · 2026-09-02
• Former Microsoft exec Edwin Arbus joins Anthropic — mhmazur · 2026-09-02
• User Celebrates Joining Anthropic with Waffle Photo — bookwormengr · 2026-09-02
• Edwin Arbuisson joins Anthropic — trq212 · 2026-09-02

1 near-duplicate retellings: davidhoang