The U.S. companion diagnostics (CDx) development market reached USD 412.84 million in 2024, with a projected CAGR of 7.8% anticipated over the forecast period from 2025 to 2034. This expansion is being driven by distinct segment-level dynamics across product types, end-user industries, and application areas. By technology, next-generation sequencing (NGS)-based assays have emerged as the fastest-growing segment, capturing significant traction due to their ability to analyze multiple biomarkers simultaneously, making them ideal for use in immuno-oncology and rare disease applications. Polymerase chain reaction (PCR) remains