humans& previously raised $480 million and just launched a new large model with improved 'collaboration capabilities.' The model itself is fine-tuned based on GLM 5.3 (seems like more teams are moving away from pre-training and instead fine-tuning open-source models to enhance specific capabilities). Use cases for the model (see image). Model highlights: Ampersand is the first model designed for long-term collaboration, aiming to help individuals and groups achieve implicit goals rather than simply completing tasks or optimizing preferences. It is fine-tuned on GLM 5.3 (approximately 744B parameters) and trained over several months using Persimmon user models in long-term multi-agent simulations. It employs a new offline RL algorithm called CORO (Contrastive Off-policy Reward Optimization) to handle asynchronous long-range rollouts. In simulation evaluations, it outperforms or matches cutting-edge models like Fable and Gemini in advancing goal value, though it has higher interaction costs (due to active coaching). The model emphasizes considering the long-term consequences of actions and group dynamics and is now available to developers for building collaborative applications via the Agents API. Team: Founded in September 2025 by Eric Zelikman (CEO, former xAI researcher involved in Grok-2 pre-training and reinforcement learning, Stanford PhD), Andi Peng (former Anthropic researcher responsible for RL and fine-tuning of Claude 3.5 to 4.5), Georges Harik (Google's 7th employee, contributed to Gmail, ad systems, and the Android acquisition), Yuchen He (former xAI), and Noah Goodman (Stanford professor of psychology and computer science). The team consists of 20-30 members, many from OpenAI, Anthropic, Google DeepMind, Meta, xAI, and others, focusing on human-centered collaborative AI. Funding: Completed a $480 million seed round in January 2026, with a valuation of $4.48 billion (one of the largest seed rounds in history). The round was led by SV Angel (Ron Conway) and co-founder Georges Harik, with participation from NVIDIA, Jeff Bezos, GV (Google Ventures), Emerson Collective, and others. Technical report: https://ampersand.humansand.ai/blog/