{"title":"The Disappearing Index Effect","authors":"ROBIN GREENWOOD, MARCO SAMMON","doi":"10.1111/jofi.13410","DOIUrl":null,"url":null,"abstract":"The abnormal return associated with a stock being added to the S&P 500 has fallen from an average of 7.4% in the 1990s to less than 1% over the past decade. This has occurred despite a significant increase in the share of stock market assets linked to the index. A similar pattern has occurred for index deletions, with large negative abnormal returns during the 1990s but an average return of only 0.1% between 2010 and 2020. We investigate the drivers of this phenomenon and discuss implications for market efficiency. We document a similar decline in the index effect among other families of indices.","PeriodicalId":15753,"journal":{"name":"Journal of Finance","volume":"32 1","pages":""},"PeriodicalIF":7.6000,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Finance","FirstCategoryId":"96","ListUrlMain":"https://doi.org/10.1111/jofi.13410","RegionNum":1,"RegionCategory":"经济学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"BUSINESS, FINANCE","Score":null,"Total":0}
引用次数: 0
Abstract
The abnormal return associated with a stock being added to the S&P 500 has fallen from an average of 7.4% in the 1990s to less than 1% over the past decade. This has occurred despite a significant increase in the share of stock market assets linked to the index. A similar pattern has occurred for index deletions, with large negative abnormal returns during the 1990s but an average return of only 0.1% between 2010 and 2020. We investigate the drivers of this phenomenon and discuss implications for market efficiency. We document a similar decline in the index effect among other families of indices.
期刊介绍：
The Journal of Finance is a renowned publication that disseminates cutting-edge research across all major fields of financial inquiry. Widely regarded as the most cited academic journal in finance, each issue reaches over 8,000 academics, finance professionals, libraries, government entities, and financial institutions worldwide. Published bi-monthly, the journal serves as the official publication of The American Finance Association, the premier academic organization dedicated to advancing knowledge and understanding in financial economics. Join us in exploring the forefront of financial research and scholarship.
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