Data and Code for: Common Ownership in America 1980-2017

We empirically assess the implications of the common ownership hypothesis from a historical perspective using the set of S&amp;P 500 firms from 1980–2017. We show that the dramatic rise in common ownership in the time series is driven primarily by the rise of indexing and diversification and, in the cross–section, by investor concentration, which the theory presumes to drive a wedge between cash flow rights and control. We also show that the theory predicts incentives for expropriation of undiversified shareholders via tunneling, even in the Berle and Means (1932) world of the widely held firm.<br><br>We include additional data on scraped SEC 13f forms for 2000-2017. The rest of the data is provided or downloaded from WRDS and requires a WRDS account.

本研究以1980—2017年的标普500（S&P 500）成分股公司为样本，从历史视角实证检验共同所有权假说（common ownership hypothesis）的理论内涵与实践影响。研究发现，共同所有权在时间序列上的显著增长主要源于指数化投资与分散化投资的扩张，而在横截面维度上则由投资者集中度推动——该理论认为，投资者集中度会在现金流权与控制权之间制造割裂。此外，本研究证实，即便在伯利和米恩斯（Berle and Means，1932）所提出的股权分散型公司语境中，该理论依然预言了通过隧道挖掘（tunneling）侵占非分散化股东利益的动机。

本研究纳入了2000—2017年间爬取自美国证券交易委员会（SEC）13F表格的额外数据集。其余数据均由沃顿研究数据服务（WRDS）提供或可从该平台下载，使用时需拥有WRDS账户。