Ultragenyx reported failure of two phase‑3 trials in brittle bone disease and announced plans for a major cost‑reduction program. The company said the late‑stage readouts did not meet endpoints and outlined a restructuring to preserve runway while it reassesses the development strategy for skeletal programs. The failures will force reprioritization across Ultragenyx’s pipeline and may affect partnerships, manufacturing plans and R&D budgets. Investors and partners will watch the company’s cost actions and any asset rationalization closely as benchmarks for broader tolerance of late‑stage failure in rare‑disease biotech.