Information Networks and Market Segmentation

Abstract

I examine how non-uniform information diffusion through distinct networks segments U.S. financial markets. Using changes in newspaper ownership networks, I document that a network link between different geographic areas leads to increased comovement of turnover and returns between stocks headquartered in those areas. Consistent with delayed content sharing within a network, the largest increase in comovement is observed using weekly data. I show that the network-driven comovement is not driven by fundamentals and is weaker for large firms with high institutional ownership and declines in the post-internet era. I also document that a network link causes price levels of linked stocks to become more similar. My findings show that segmented information networks lead to segmented financial markets with implications for market efficiency, home bias, and the effects of changes in the U.S. media landscape on financial markets.