Synopsys is trading 10.05% higher at $478.64 after announcing a multi-year partnership with OpenAI on September 30, 2026. - The companies plan to develop GPT-Synopsys, a specialized AI model for using Synopsys tools in semiconductor-design workflows; the deal includes revenue sharing and a joint go-to-market effort. - Reuters reported the deal. Synopsys closed September 30 at $434.94, up 4.78%; the live quote shows further gains during the October 1 session, while broader indexes were only modestly higher.