Administrative division adjustments and stock price comovement: Evidence from the city–county mergers in China

Under the background of Chinese market segmentation, whether government-led administrative division adjustments can promote regional economic integration is a practical issue. Taking interregional firms’ stock price comovement as a micro measurement of regional integration, this paper investigates the regional integration effect of administrative division adjustments, i.e., city–county mergers. We find that stock price comovement between county-level and municipal district-level firms in the merged counties and municipal districts significantly improve after city–county mergers, particularly in regions with a higher degree of market segmentation and lower degree of marketization. We further find that the increase in stock price comovement caused by city–county mergers emerges from the increase in comovement of real activities between firms in the merged counties and municipal districts. Taken together, our results suggest that government-led administrative division adjustments effectively promote regional integration.