Tempus AI agreed to buy Personalis in a $1.5 billion deal, expanding its minimal residual disease (MRD) diagnostics footprint. Under the terms, Personalis shareholders will receive $16.25 per share, a premium to the prior close, and Tempus expects the transaction to close late 2026 or early 2027 subject to approvals. The acquisition builds on a partnership announced in 2023, in which Tempus invested in Personalis and co-commercialized Personalis’ tumor-informed MRD test. Tempus said it expects the combined capabilities—linking MRD sensitivity to its multimodal data and AI systems—to strengthen biomarker discovery and personalized oncology offerings. Personalis reported preliminary second-quarter revenue of $22.4 million and test volumes increasing quarter-over-quarter. The deal also reflects continued investor and payer interest in MRD assays that can guide treatment selection, monitor recurrence, and refine clinical decision-making.