Urban Vibrancy and Corporate Growth
研究发现企业投资对邻近企业（包括不同行业）的投资高度敏感，且受当地非同行企业现金流和股价波动影响，表明集聚经济是企业投资和增长的重要决定因素。
ABSTRACT We find that a firm's investment is highly sensitive to the investments of other firms headquartered nearby, even those in very different industries. A firm's investment also responds to fluctuations in the cash flows and stock prices ( q ) of local firms outside its sector. These patterns do not appear to reflect exogenous area shocks such as local shocks to labor or real estate values, but rather suggest that local agglomeration economies are important determinants of firm investment and growth.