SangBin Cho

Scaling RL @meta | prev RL @xAI | founding engineer @anyscalecompute | committers of @raydistributed @vllm_project Sglang | Github: rkooo567

[SangBin Cho @Saaaang94]

RT @gdb: Rust is great

[Noam Brown @polynoamial]

I'm always thrilled to have more Noams at @OpenAI, but I'm especially thrilled to welcome @NoamShazeer!

[Noam Shazeer @NoamShazeer]

I’m excited to share that I’ll be joining OpenAI and look forward to working with the exceptional team there.

It was a difficult decision to move on. I’m incredibly proud of the amazing team at Google and everything we’ve built together. It has been an honor and a pleasure to work with all of you.

[Michael Truell @mntruell]

Lots to do together. Excited to be joining forces with @SpaceX to build useful AI.

[KAIST AI @KAIST_AI]

📢 Three incoming faculty members at KAIST AI, starting in August 2026✨
Dr. Sehoon Kim from xAI (@sehoonkim418), Dr. Hyunwoo Kim (@hyunw_kim), and Dr. Seung Wook Kim (@seungkim0123), both from NVIDIA, will be joining KAIST AI as Assistant Professors

Check their websites below🧵

[Goldman Sachs @GoldmanSachs]

SpaceX is redefining industries on Earth and aiming to create new ones beyond it.

On June 11, it successfully priced its $75B IPO.

Goldman Sachs is honored to have served as lead left bookrunner.

[Morgan Stanley @MorganStanley]

Today, @SpaceX (Nasdaq: SPCX) makes its public market debut with a $75Bn offering (pre-greenshoe) at $135 per share, marking the largest IPO in history.

Congratulations to the SpaceX team. We are honored to serve as joint lead bookrunner and sole stabilization agent.

[Dario Amodei @DarioAmodei]

Today I'm publishing a new essay, Policy on the AI Exponential. AI is progressing extremely fast—much faster than the policy process was built to handle. The essay lays out where I think the technology is now, and the action needed to close the gap: https://t.co/Lh6PWae178

[SangBin Cho @Saaaang94]

@simon_mo_ @BugenZhao Good direction!

[Michael Truell @mntruell]

Composer 2.5 is now the most-chosen model in Cursor.

We're giving everyone 10x usage for the rest of the day. Enjoy!

[Andrej Karpathy @karpathy]

Personal update: I've joined Anthropic. I think the next few years at the frontier of LLMs will be especially formative. I am very excited to join the team here and get back to R&D. I remain deeply passionate about education and plan to resume my work on it in time.

[Simon Mo @simon_mo_]

Very importantly! We have a beautiful patio on Market Street.

[Joey Gonzalez @profjoeyg]

Today I’m excited to congratulate @simon_mo_ on an outstanding PhD thesis defense on his work exploring the design of Inference Serving Systems. 🎉

Simon has been working on inference systems with me for nearly a decade -- long before most people even considered inference serving a research problem worth studying.

Over that time, he helped drive inference systems projects spanning Clipper, @raydistributed Serve, and now @vllm_project. Together, these systems helped define the modern inference serving stack that powers today’s AI applications.

Beyond being an exceptional researcher, Simon has also been a remarkable team and community builder, especially through his leadership on vLLM and the open-source ecosystem around it.

Along with my colleagues @istoica05 and @koushik77, I am excited to see Simon leading @inferact as CEO and helping shape the future of inference systems and AI infrastructure.

Congratulations, Simon!

[RadixArk @radixark]

Today, we are thrilled to officially launch RadixArk with $100M in Seed funding at a $400M valuation. The round was led by @Accel and co-led by @sparkcapital.

RadixArk exists to make frontier AI infrastructure open and accessible to everyone. Today, the systems behind the most capable AI models are concentrated in a small number of companies. As a result, most AI teams are forced to rebuild training and inference stacks from scratch, duplicating the same infrastructure work instead of focusing on new models, products, and ideas.

RadixArk was founded to change that. We are building an AI platform that makes it easier for teams to train and serve the best models at scale.

RadixArk comes from the open-source community. We started with SGLang, where many of us are core developers and maintainers, and expanded our work to Miles for large-scale RL and post-training. We will continue contributing to both projects and working with the community to make them the strongest open-source infrastructure foundations for frontier AI.

We would like to thank our long-term partners, contributors, and the broader SGLang community for believing in this mission. We're also grateful to @Accel and @sparkcapital, NVentures (Venture capital arm of @nvidia), Salience Capital, A&E Investment, @HOFCapital, @walden_catalyst, @AMD, LDVP, WTT Fubon Family, @MediaTek, Vocal Ventures, @Sky9Capital and our angel investors @ibab, @LipBuTan1, Hock Tan, @johnschulman2, @soumithchintala, @lilianweng, @oliveur, @Thom_Wolf, @LiamFedus, @robertnishihara, @ericzelikman, @OfficialLoganK, and @multiply_matrix among others.

Thanks for the exclusive interview with @MeghanBobrowsky at @WSJ about our vision.

[Jack Rae @jack_w_rae]

Nice debut from Muse Spark in the Agentic Coding arena.

Ranking ahead of GPT 5.4 and Gemini models, and behind the Opus series + GLM 5.1.

[Jerry Tworek @MillionInt]

Small step for a finger on "post tweet" button.

Big step for millions of future AI agents doing useful work for us.

[Core Automation @CoreAutoAI]

Today we're announcing Core Automation

Our objective: systems that optimize and automate work, starting with research itself.

[Alexandr Wang @alexandr_wang]

okay this is too exciting :)

meta AI is now #2 in the app store, top AI app!

we are so back!

[Alexandr Wang @alexandr_wang]

the muse spark API will be coming soon!

we have been thrilled with the amount of excitement amongst developers who want to try muse spark inside their agentic harnesses

stay tuned!

[Hongyu Ren @ren_hongyu]

Check out Muse Spark, our first milestone in the quest for personal superintelligence! Scaling this with the team has been a total blast. Give it a spin and let us know what you think! 🥑