The Price of Street Friends: Social Networks, Informed Trading, and Shareholder Costs
研究发现，公司与投资界之间的社交联系会显著增加股票交易成本，基于教育和休闲活动的强联系以及负责交易的人员联系影响更大；利用投资关系人死亡作为自然实验，证实切断联系会降低交易成本和关联方的交易活动。
Abstract Recent studies suggest the transfer of privileged information via social ties but do not explicitly examine the cost of these ties to shareholders. We document a significant positive relation between stock transaction costs and a company’s social ties to the investment community. Social ties based on education and leisure activities, stronger ties, and ties to individuals responsible for trading have greater effects. Using investment connection deaths as natural experiments, we document that exogenous severance of ties reduces trading costs and trading activities by connected parties. Our evidence illustrates an important and previously undocumented consequence of social ties.