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Dec 5 6 tweets 4 min read Read on X
To mark the 2nd anniversary of LLM360, we are proud to release K2-V2: a 70B reasoning-centric foundation model that delivers frontier capabilities.

As a push for "360-open" transparency, we are releasing not only weights, but the full recipe: data composition, training code, logs, and intermediate checkpoints.

About K2-V2:

🧠 70B params, reasoning-optimized
🧊 512K context window
🔓 "360-Open" (Data, Logs, Checkpoints)
📈 SOTA on olympiad math and complex logic puzzlesImage
We evaluated K2 across general knowledge, STEM, coding, and agentic tool use.

The goal? To show open models need not be smaller, weaker versions of closed ones.

K2 outperforms models of similar sizes, and performs close to models that are larger.

🔗 Check out the model here:

Generously sponsored by @mbzuai.huggingface.co/LLM360/K2-V2Image
K2 introduces three "reasoning effort" modes—Low, Medium, and High—allowing you to balance cost vs. capability.

K2-High excels on hard math tasks like AIME 2025 (80.2%) and HMMT, while K2-Medium is the sweet spot for efficiency. Image
True openness means shipping the artifacts others hide. We release K2 components in three suites 📕

1. Full checkpoints (including mid-training), logs, and code.

2. Exact data recipes and curation details.

3. The "TxT360-3efforts" SFT data to teach models to think.
The secret sauce is our "Mid-Training" phase.

We didn't only fine-tune; we infused reasoning early by feeding K2 billions of reasoning tokens and extending context to 512K tokens.

This ensures reasoning is a native behavior. See how K2-High achieves state-of-the-art results by leveraging more "thinking tokens."Image
Ready to dive in?

📄 Technical Report: llm360.ai/reports/K2_V2_…

🤗 Model & Data: huggingface.co/collections/LL…

📊 Analysis: wandb.ai/llm360/K2-V2

💻 Training Code: github.com/llm360/k2v2_tr…

💻 Evaluation Code: github.com/llm360/eval360

A huge thank you to the OSS ecosystem! @huggingface @wandb @github @lmsysorg @AiEleuther @allen_ai @BigCodeProject @PyTorch @nvidia @cerebras @mbzuai and many more.Image

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More from @llm360

Apr 11
Proudly present MegaMath, the largest open-source math reasoning pretraining corpus—371B tokens of high-quality mathematical web, code, and synthetic data, designed to build the data foundation for next-generation math-proficient LLMs like o1 and R1. 🧵👇 #LLM #OpenSource #MegaMath #Math #Data4LLMs #Pretraining

Trending now on Hugging Face: huggingface.co/datasets/LLM36…MegaMath Overview
🔍 Why is this important?

Mathematical reasoning is a key feature of advanced LLMs. Training math-proficient models like O1 and DeepSeek-R1 requires large-scale, high-quality, diverse math data. Proprietary corpora, such as Qwen-2.5-Math (1T) and DeepSeekMath (120B), show strong mathematical abilities but are closed source. Existing open corpora lack comparable size and quality. MegaMath aims to bridge this gap.Image
💡 What’s in MegaMath?
MegaMath is a comprehensive 371B-token collection delivering with top data quality. It is composed of:

📚279B tokens of math-rich web data
🧑‍💻 28B tokens of math-relevant code
🧠64B tokens of high-quality synthetic data (QA pairs, translated code, text+code blocks)Image
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