Outsourced Semiconductor Assembly and Test (OSAT) market is estimated at USD 69,587.4 million in 2026, and is projected to reach USD 104,389.4 million by 2034, expanding at a 5.2% CAGR during 2026–2034. Asia Pacific is the largest region because merchant packaging and test capacity, semiconductor manufacturing, substrate ecosystems and major OSAT headquarters are heavily concentrated across Taiwan, China, South Korea, Malaysia, Singapore and other Asian production hubs.