PDF(Pubmed)
Abstract：
BACKGROUND: Recent studies document the rising prevalence of common ownership by institutional investors in specific industries. Those investors offer products, such as mutual and index funds, to trade securities on behalf of others and often own shares of multiple firms in the same industry to diversify portfolios. However, at present, few studies focus on common ownership trends in health care.
OBJECTIVE: This paper examines institutional investors\' common ownership in the major insurers offering plans in the Medicare Part D stand-alone prescription drug plan (PDP) market between 2013 and 2020.
METHODS: Using data from the Securities and Exchange Commission (SEC) database and the Center for Research in Securities Prices, we compute the percentages of outstanding shares of each insurer owned by institutional investors. Data visualization and network analysis are employed to assess the trends in common ownership among major insurers.
RESULTS: We document a high prevalence of and substantial increase in shared institutional investors in the PDP market. From 2013 to 2020, the degree of common ownership increased by 7% on average, and the common ownership network became more connected. Common ownership also varies across the 34 PDP regions depending on their reliance on listed insurers, that are traded in the stock exchange, offering stand-alone PDPs.
CONCLUSIONS: High and rising common ownership in the Medicare Part D PDP market raises policy questions about potential effects on plan offerings, premiums, and quality for consumers.
OBJECTIVE: This paper examines institutional investors\' common ownership in the major insurers offering plans in the Medicare Part D stand-alone prescription drug plan (PDP) market between 2013 and 2020.
METHODS: Using data from the Securities and Exchange Commission (SEC) database and the Center for Research in Securities Prices, we compute the percentages of outstanding shares of each insurer owned by institutional investors. Data visualization and network analysis are employed to assess the trends in common ownership among major insurers.
RESULTS: We document a high prevalence of and substantial increase in shared institutional investors in the PDP market. From 2013 to 2020, the degree of common ownership increased by 7% on average, and the common ownership network became more connected. Common ownership also varies across the 34 PDP regions depending on their reliance on listed insurers, that are traded in the stock exchange, offering stand-alone PDPs.
CONCLUSIONS: High and rising common ownership in the Medicare Part D PDP market raises policy questions about potential effects on plan offerings, premiums, and quality for consumers.
摘要：
背景：最近的研究记录了特定行业中机构投资者共同所有权的日益普遍。那些投资者提供产品，例如共同基金和指数基金，代表他人进行证券交易，并经常拥有同一行业多家公司的股份，以使投资组合多样化。然而,目前,很少有研究关注医疗保健的共同所有权趋势。
目的：本文研究了机构投资者在2013年至2020年间在MedicareD部分独立处方药计划（PDP）市场提供计划的主要保险公司的共同所有权。
方法：使用美国证券交易委员会（SEC）数据库和证券价格研究中心的数据，我们计算机构投资者持有的每家保险公司流通股的百分比。数据可视化和网络分析用于评估主要保险公司共同所有权的趋势。
结果：我们记录了PDP市场中共享机构投资者的高流行率和大幅增长。从2013年到2020年，共有程度平均增加了7%，共同所有权网络变得更加紧密。34个PDP地区的共同所有权也有所不同，具体取决于它们对上市保险公司的依赖程度，在证券交易所交易，提供独立的PDP。
结论：MedicareD部分PDP市场的高和不断上升的普通股所有权引发了有关对计划产品的潜在影响的政策问题，保费，和消费者的质量。
目的：本文研究了机构投资者在2013年至2020年间在MedicareD部分独立处方药计划（PDP）市场提供计划的主要保险公司的共同所有权。
方法：使用美国证券交易委员会（SEC）数据库和证券价格研究中心的数据，我们计算机构投资者持有的每家保险公司流通股的百分比。数据可视化和网络分析用于评估主要保险公司共同所有权的趋势。
结果：我们记录了PDP市场中共享机构投资者的高流行率和大幅增长。从2013年到2020年，共有程度平均增加了7%，共同所有权网络变得更加紧密。34个PDP地区的共同所有权也有所不同，具体取决于它们对上市保险公司的依赖程度，在证券交易所交易，提供独立的PDP。
结论：MedicareD部分PDP市场的高和不断上升的普通股所有权引发了有关对计划产品的潜在影响的政策问题，保费，和消费者的质量。
