Thomson Reuters (Nasdaq: TRI) announced the launch of Thomson, its first in-house developed large language model (LLM), according to a company press release dated Aug. 24, 2026.

The company said it invested $40 million to train the model, covering talent and compute costs, starting from an open-source foundation. Thomson Reuters said it fully owns and controls the model, without the higher inference costs associated with typical frontier models.

Thomson was trained on proprietary content from Thomson Reuters platforms including Westlaw, Practical Law, Checkpoint, and Reuters. The company said the model has so far been trained on less than 10% of its total content library.

Thomson Reuters Chief Technology Officer Joel Hron said in a statement: "Start with a strong foundation, specialize it deeply for the work that matters, and you can build intelligence that is highly capable, far more efficient and entirely under your control."

CEO Steve Hasker said early evaluations placed Thomson "on par with the latest frontier models across a range of tasks," though the company did not name the specific models used for comparison.

The model's first deployment is within the Tabular Analysis feature of CoCounsel Legal, the company's legal AI product aimed at law firms and corporate legal departments. Thomson Reuters said CoCounsel Legal will remain multi-model, using Thomson where it provides the clearest advantage alongside other models.

Ahead of the public launch, Thomson Reuters made the model available to a group of legal and AI academics for evaluation. The company is also releasing a smaller version of Thomson as an open-weight model on Hugging Face for academic and non-commercial use.

Two external evaluators provided assessments. Jonathan H. Choi of Washington University School of Law said he preferred Thomson's responses to those of ChatGPT and Claude on corporate tax questions, citing its links to treatises. Professor Samuel Dahan of Queen's Conflict Analytics Lab and Cornell Legal AI Lab said Thomson's citation quality was "generally competitive with leading frontier models" in Canadian employment law testing.

Thomson Reuters said it plans to extend Thomson models across its legal and tax product portfolio, with additional sovereign AI options to follow.