Investment Trend and Industrial Upgrading Under RCEP in Thailand: Uncertainty Reduction, Institutional Facilitation, and Industrial Transformation in Thailand

This study examines changes in Thailand’s investment trends and industrial structure during the early implementation of the Regional Comprehensive Economic Partnership (RCEP), comparing the pre-RCEP period (2015–2021) with the early post-RCEP period (2022–2025). The study uses secondary data from the Thailand Board of Investment (BOI) and applies a descriptive analytical approach using three indicators: Return on Investment (ROI), Industrial Structure Optimization Rate (ISOR), and the Herfindahl–Hirschman Index (HHI). The findings indicate changes in the sectoral composition of FDI during the post-RCEP period, with increased investment activity in technology-intensive and higher-value-added sectors, particularly electronics, new-energy vehicles (NEVs), and advanced manufacturing. China also became an increasingly important source of investment, accounting for 22.32% of FDI in 2023. Changes in ISOR values indicate shifts in the relative distribution of FDI toward selected technology-intensive sectors, while the decline in average HHI from 843.69 during the pre-RCEP period to 782.95 during the post-RCEP period indicates a less concentrated distribution of FDI across the six selected sectors. ROI provides supplementary evidence of differences in the relationship between FDI input and changes in sectoral value added across broad economic sectors. Overall, the findings show that changes in Thailand’s investment composition, technological orientation, and sectoral concentration coincided with the early implementation of RCEP. However, these patterns cannot be attributed to RCEP alone because post-COVID-19 recovery, domestic investment policies, global supply-chain restructuring, and geopolitical and economic conditions may also have influenced investment decisions. The findings provide descriptive evidence that can inform investment promotion, industrial upgrading, and institutional policy in Thailand and other RCEP member economies.