
Leading Reinforcement Learning at @Reflection_ai. Scaling RL for frontier reasoning models. Formerly @OpenAI, @GoogleBrain and @stanford_ee.
San Francisco, CA
Joined December 2017
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Seeing capabilities like this emerge is one of the most exciting parts of pushing the frontier of RL.
In this demo, Beam was prompted to create a live updating map of the NYC subway. Beam used the publicly available NYC MTA data, checked authentication requirements, and found subway and map geometries. Beam also built the right front and backend so the server keeps pulling live MTA updates.
This shows Beam’s RL training developed reasoning capabilities that allows it to generalize across domains like ML workflows.
Really proud of Beam, our first-ever release! Among US open-weight models tested by Artificial Analysis, it ranks #2 on the Intelligence Index and #1 on the Cyber Index.
So grateful to the team for the work that went into this. We're just getting started 🚀
Reflection’s first model, Beam, scores 30 on the Artificial Analysis Intelligence Index, placing it #2 among US open weights models
Beam is an open weights model with 501B total and 23B active parameters, released on @huggingface
Congratulations to @reflection_ai on the release!
Key takeaways:
➤ Second among US open weights models: Beam scores 30, behind only Meta's Muse Spark Open (39) and ahead of yesterday’s NVIDIA Nemotron 3.5 Super VL (26) release. Outside China, only Muse Spark Open and the UAE's K2 Horizon (31) score higher
➤ Token efficient for its intelligence: Beam uses ~26k output tokens per Intelligence Index task compared to K2 Horizon, one point ahead, which uses twice as many (~52k). Proprietary models still set the frontier, with GPT-6 Astra (max) scoring 53 on the same budget (~27k)
➤ Strong on agentic workflows, weaker in the terminal: Beam scores 48.5% on AutomationBench-AA, 11 percentage points ahead of K2 Horizon (37.2%) and level with Qwen3.8 27B (48.2%). Terminal-Bench 4.0 is a weak point, where Beam scores 3.0%, behind Qwen3.8 27B (5.6%) and Muse Spark Open (8.1%)
➤ Knows more, guesses more: On AA-Omniscience it answers 33% of questions correctly, well ahead of K2 Horizon (18%) and Qwen3.8 27B (16%). But its hallucination rate is 47%, against 26% for K2 Horizon and 30% for Qwen3.8 27B, giving Beam a net index score of 1.5, ahead of both peers (−3.0 and −10.0)
Other model details
Context window: 1M tokens
Modalities: Text
Parameters: 501B / 23B
Behrooz Ghorbani retweeted
Incredibly proud of @reflection_ai for immediately jumping into the #2 spot for US open models with their first ever model. Beam is SO fast and efficient for its size. Check it out
Reflection’s first model, Beam, scores 30 on the Artificial Analysis Intelligence Index, placing it #2 among US open weights models
Beam is an open weights model with 501B total and 23B active parameters, released on @huggingface
Congratulations to @reflection_ai on the release!
Key takeaways:
➤ Second among US open weights models: Beam scores 30, behind only Meta's Muse Spark Open (39) and ahead of yesterday’s NVIDIA Nemotron 3.5 Super VL (26) release. Outside China, only Muse Spark Open and the UAE's K2 Horizon (31) score higher
➤ Token efficient for its intelligence: Beam uses ~26k output tokens per Intelligence Index task compared to K2 Horizon, one point ahead, which uses twice as many (~52k). Proprietary models still set the frontier, with GPT-6 Astra (max) scoring 53 on the same budget (~27k)
➤ Strong on agentic workflows, weaker in the terminal: Beam scores 48.5% on AutomationBench-AA, 11 percentage points ahead of K2 Horizon (37.2%) and level with Qwen3.8 27B (48.2%). Terminal-Bench 4.0 is a weak point, where Beam scores 3.0%, behind Qwen3.8 27B (5.6%) and Muse Spark Open (8.1%)
➤ Knows more, guesses more: On AA-Omniscience it answers 33% of questions correctly, well ahead of K2 Horizon (18%) and Qwen3.8 27B (16%). But its hallucination rate is 47%, against 26% for K2 Horizon and 30% for Qwen3.8 27B, giving Beam a net index score of 1.5, ahead of both peers (−3.0 and −10.0)
Other model details
Context window: 1M tokens
Modalities: Text
Parameters: 501B / 23B
Behrooz Ghorbani retweeted
Beam is now available across platforms, with open weights under the Apache 2.0 license - in collaboration with an ecosystem of 40+ partners.
We're releasing:
- Weights, tokenizer, and reference implementation
- BF16, FP8 and NVFP4 weights and a DFlash2 drafter
- The open source harness we built and trained Beam on: Mirror CLI
Weights and model card on Hugging Face: huggingface.co/reflection
Behrooz Ghorbani retweeted
This was the first big run we've done at Reflection. We had a so much fun running a lot of RL on this one! It was very satisfying to see scaling RL in action with no plateau in sight!
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Behrooz Ghorbani retweeted
I really liked Reflection CEO @MishaLaskin's framing on the state of closed vs. open AI models:
"Closed models are the equivalent in real estate to renting an apartment... As AI adoption has increased, an ownership market is basically coming in.. The only way to own intelligence, by definition, is if it's open"
Reflection’s founders on building a DeepSeek of the West
Reflection is soon releasing Beam, its first open-weight AI model, in a bid to become the DeepSeek of the West. Trained from scratch, Beam is designed for coding, reasoning, and AI agents. Reflection's benchmarks put it alongside the strongest open models, with substantially more efficient token economics.
To mark Beam’s debut, I'm joined by Reflection's co-founders: CEO @MishaLaskin, who led reward modeling for Google’s Gemini, and CTO @real_ioannis, who helped create AlphaGo and AlphaZero before leading Gemini’s RLHF effort. Reflection has raised $4.6 billion from investors that include Nvidia, Sequoia, and Lightspeed.
We discuss why Chinese labs pulled ahead in open AI models, how Reflection built Beam, and why the founders think companies and countries will increasingly want to control their own models. I ask how they plan to make money from open-weight AI, whether openness can make these systems safer, and what comes next for Reflection.
Timestamps:
00:00 Why open models are surging
01:06 Renting vs. owning intelligence
03:40 Open models catch up
05:53 Why China led open AI
08:03 Introducing Beam
10:05 Scaling reinforcement learning
14:09 Training from scratch
16:04 Safety, alignment and openness
32:29 The Reflection origin story
37:32 Making money on open models
42:33 Vertical integration and compute
48:45 Partnerships and distribution
56:46 What’s next for Reflection
Links: podcast.sources.news/
Spotify: open.spotify.com/show/3p1KZv…
YouTube: youtu.be/BKnAeVej0dc
Substack: sources.news/p/reflection-fo…
Thanks to the show’s premier sponsors: @Atlassian, @meetgranola, and @mercury.
Behrooz Ghorbani retweeted
the chinese open weight frontier has been running without a serious western peer for a while, but today reflection dropped beam!
underneath there's a super solid team:
- ex-deepmind founders (@MishaLaskin / @real_ioannis)
- $4.6b raised,
- $25b mark, nvidia in the round.
- 23.8t pretrain on 6,144 GB300s
- then 10.5k gb300s for four weeks of rl
- 100m+ rollouts
- locked spacex colossus GB300 capacity
- locked $1b $NBIS compute deal (we announced this few months ago, letsgoooo)
- 501b total, 23b active, sparse MOE, trained from scratch, coding and agents first.
On their numbers it basically ties glm-5.2 on the agentic coding rows that matter for a workhorse:
- deepswe 44.4 vs 44
- terminal-bench 80 vs 81
but all this while using roughly 3 to 4x less inference compute for similar reasoning scores, quite cool!
it still trails glm-5.3 and deepseek v4.1 flash on those same benches tho (flash is a different animal anyway: tiny active count, multimodal). And yes kimi k3 stays ahead on raw capability.
So yes the western push is real, but part of product is efficiency (at least on this one)
closed frontier (opus / astra lvl) still owns the top of the capability curve but Beam isn’t pretending otherwise.
i guess it's fair if you compare open to open, and having a western model you can own that sits in glm 5.2’s neighborhood at a fraction of the reasoning compute, is quite impressive
as Laskin said: closed models are renting an apartment, an ownership market is forming. This is the first well-funded western open workhorse built for that
We are introducing Beam today, a 500b open model that excels in coding, agentic, and scientific workloads.
Beam is very token-efficient, pre-trained from scratch, and scaled with the largest RL run documented openly we are aware of.
Getting here was challenging, rewarding, and personal.
I immigrated to the USA during childhood when my parents got jobs as scientists at PNNL, a national lab located in a rural town in Washington state.
Growing up, I developed an interest in physics because it was grounded in simple principles, was foundational, and had long-term impact.
Physics was the foundational science of the 20th century. The first general computer (ENIAC), the transistor, GPS, and much of modern technology had its roots in physics.
In 2016, during my graduate studies, I noticed the birth of a new foundational science - Artificial Intelligence.
AlphaGo, the superintelligent Go agent developed by DeepMind, had come out and made me feel what was about to come.
A neural network, trained to imitate human players, and then improve itself through trial and error, mastered the most intellectually challenging board game in the world.
What surprised me about AlphaGo is how it was conceptually simple, general, and scalable. The system could in principle improve itself forever, it was just a function of compute.
This is when I became “AGI pilled” as they say.
I switched from physics to AI because I thought this would become the root node science of the 21st century, much like physics was the root node science of the 20th century.
I believe that working on foundational science is not enough on its own. Foundational science must also remain open and widely accessible.
We remember Newton for his contributions to physics, but he was also an alchemist.
Alchemy was done in secret, because the artificial production of gold was deemed lucrative but also dangerous with the potential do destroy entire economies. Newton even wrote his alchemy notebooks in cypher.
On the other hand, Principia was published in the Philosophical Transactions of the Royal Society, the knowledge was made widely available, passed down for generations in what we now call Newton’s laws.
The computer, transistor, GPS were possible to build because physics as a science was open. Openness creates an ecosystem of innovation.
The notion of openness, which is a core tenet of scientific discovery, has also become a guiding principle for how foundational technology gets built and distributed.
The internet was built on open protocols. The most widely used operating systems are open. The field of cybersecurity exists because strong encryption protocols were made open in the 1990s.
Open also means safer. The best defence is a distributed one. Commonly used open source software is robust and battle-tested because it is inspected and patched by a community of developers.
AI is different but also similar to software in many ways, though with a much larger surface area of vulnerabilities. It is impossible for a small group of safety researchers working in secrecy to remediate all of the potential issues regardless of their intentions. It is like entrusting a handful of white blood cells to protect your body.
AI is both foundational as a science and a technology, and the safest way that also ensures the benefits of AI are distributed evenly is by making it open.
I’m excited for what developers and scientists build and learn from this model, and for Beam to play a small part in ensuring that AI is made widely accessible, safe, and beneficial to all.
Behrooz Ghorbani retweeted
We scaled Beam with the largest publicly documented RL run we’re aware of, which ran on 10.5k GB300s for 4 weeks.
Algorithmic advances coupled with distributed infra enabled an RL system that scales.
Across our eval suite, capabilities continued to improve as we increased RL - with no signs of plateau.
Behrooz Ghorbani retweeted
Artificial Analysis has been given access by Reflection and is independently benchmarking Beam
Early indicators suggest Beam will be one of the most token-efficient open models we've seen for its level of intelligence.
Congratulations @reflection_ai on the announcement!
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Behrooz Ghorbani retweeted
Flash models are where the volume is. DeepSeek V4.1 Flash and GLM 5.3 Flash lead OpenRouter’s 30-day token rankings. The models people actually deploy deserve more attention.
This is why Reflection’s Beam matters. It has 501B total parameters but activates only 23B per token. Reflection reports GLM-5.2-class reasoning on selected benchmarks at roughly one-quarter to one-third the estimated generation compute.
Open weights give developers another way to improve those economics. Beam’s Apache 2.0 release is planned for later this month, allowing developers to customize the model and optimize how they serve it.
Reflection is bringing frontier intelligence to an economically useful parameter size, then letting everyone build on it, unlocking an enormous amount of latent demand.
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Behrooz Ghorbani retweeted
Introducing Beam: frontier reasoning at 4x the efficiency of today’s leading Western open models.
Beam is the first in a series, and we’re just getting started. We want to put more control in users hands - with sovereignty, continuity, and lower costs - and help grow a strong U.S. open ecosystem where frontier labs build on each other’s work and push one another forward.
What a team. What a moment. So proud of the people behind this and so grateful to be part of it.
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Behrooz Ghorbani retweeted
It’s a huge honour to be part of the team building the open weights frontier. 🙏
Super excited for everyone to try this!
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Behrooz Ghorbani retweeted
Congrats to Reflection for launching their first model! It took a while but they got there😄
Looks like a GLM-5.2-level model, perhaps the best American open-source model?
Weights will be released soon...
Overall, it's great to have another strong open-source player in the US
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Behrooz Ghorbani retweeted
Today, we’re introducing Beam, Reflection’s first model.
A year ago, we set out to build a frontier open model before we had much of the team or infrastructure required to do it.
Since then, Reflection has grown 10x. We assembled an extraordinary technical team of researchers and engineers I feel privileged to call my colleagues, alongside a world-class group across recruiting, business, policy, operations, and the rest of the company whose work made all of this possible.
At the same time, we built the science, data, software, and infrastructure behind the model itself. In July, we started pretraining Beam and weeks later, we had a 500B-parameter model at the frontier of Western open intelligence—particularly strong at agentic coding, with remarkable reasoning efficiency.
What makes me proudest, though, is our team. The relentless focus, speed of execution and the willingness to own and solve whatever problem was in front of us. And, most importantly, the commitment of this team to our mission.
Beam is our first milestone toward our mission of building open intelligence and making it accessible to everyone.
We’ll release Beam’s weights, model card, and tech report later this month.
And we’re already training the next, larger model.
Over the past year, we built the team and the engine to propel us to the frontier and that’s what makes me so excited about what comes next.
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Behrooz Ghorbani retweeted
Fun time cooking this up with an awesome team! More to come soon 🚀🚀🚀
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Behrooz Ghorbani retweeted
We built our first model!! Beam is a competitive text-only 501B-A23B MoE, openly released under the Apache 2.0 license
It’s been fun scaling the production RL/OPD stack for this over the past year. I’m so proud of the team! We attained exactly what we set out to do and ended up with a stable run on 10K GB300s that produced more than 100M rollouts across ~1M tasks that significantly improved the final performance of the model
👇 many more details in our announcement below :)
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
Today, we’re introducing Beam, @reflection_ai's first model.
We started the high-compute RL team in February. Looking back at these past few months, it’s remarkable how far we’ve come.
Making RL work at this scale took careful science, scalable infrastructure, and a strong foundation from mid-training. Seeing that work come together to keep learning stable as we pushed the scale and complexity of the run has been incredibly rewarding.
What has made this especially meaningful is the people: their commitment and curiosity, the way they supported one another through difficult stretches, and the joy of figuring things out together.
To everyone who helped bring Beam to life, across RL science, infrastructure, mid-training, pretraining, and our close collaborators throughout Reflection: thank you. There is so much of your hard work and care in this model.
Building and leading this team has been an honor and one of the most rewarding experiences of my career. I’ve learned so much from the people around me, and I’m proud of what we’ve built together.
@MishaLaskin and @real_ioannis, thank you for your trust and support throughout this journey.
This is our first model, and there’s so much more ahead. I’m excited to share Beam with the community, learn from your feedback, and continue building better models together.
Introducing Beam: a highly efficient agentic open model with 501B total parameters and 23B active.
- Frontier reasoning efficiency
- Advances the Western open frontier on coding & agentic tasks
- Trained end-to-end from scratch
Full weights release this month.
Learn more about Beam: reflection.ai/beam
A few personal thank-yous to @sahnihim, @MarkoRadmilac, @mojan_jp, @psanfernandes, @francismccann14, @sygiii, @suriyagnskr, and Jessica Hamrick. Your leadership and judgment shaped so much of the work behind Beam, and your dedication helped carry it through the hardest stretches.
Thank you, and thank you to everyone who worked alongside you to make this possible. I’m proud of what we’ve accomplished together and grateful to work with you all.
Huge congratulations to @bneyshabur, @HarshMeh1a, @shayan_, and @tararezaeikh on launching @mirendil! AI for science is one of the most important frontiers, and I can’t wait to see this exceptional team accelerate discovery.
Today, I’m excited to formally announce @mirendil with my amazing co-founders Harsh Mehta, Shayan Salehian, and Tara Rezaei!
We’re fortunate to work with @a16z and @kleinerperkins, who led our seed round of $200M, followed by a major investment from NVIDIA, among others.
Mirendil exists to accelerate science and technology, and through them, to help solve humanity's most pressing problems.
Self-accelerating AI R&D is the most direct path to delivering on AI's broader promise, which is why we believe the most important application of AI is AI itself. Get this loop right, and it compounds. It fundamentally changes the rate of progress itself across all domains.
We believe this capability should be democratized. It should be used to power all scientific efforts trying to innovate at the frontier. There are far more important problems—and broader ones—than any single lab can take on, so more groups should be able to pursue them.
This pulls concentration of power away from a few labs: businesses and science labs can own their AI and infrastructure, keep their margins, and control their own destiny instead of ceding it all to a single AI lab.
We’re a small team with a singular focus. Our founding team consists of 20 researchers and engineers from frontier institutions including Anthropic, xAI, Google DeepMind, and OpenAI, united by a passion for science and a drive to build the technologies that move it faster. If you want to build the system that builds systems, join us!
@HarshMeh1a, @shayan_, @tararezaeikh
Behrooz Ghorbani retweeted
I’m joining the OSS team at @reflection_ai! 🙏
My life mission has always been to work on open intelligence but there was always a missing piece in my skills:
PyTorch taught me the magic of combining Infra knowledge with applied research
@joespeez allowed me to be the dumbest person in the room and I learned more from him in those months than all years of my career.
It was a total intern feeling and was the happiest I’ve felt in a while.
I was convinced that working on OSS infra and applied research should be my next chapter.
I’m very grateful to @MishaLaskin and @real_ioannis to allowing me to be a part of the dream
To stronger chai and greater learnings at the frontier!























