24期编辑：蔡婉秋 审核：丁克达How Have Stock Markets Responded to 35 Years of Analyst Reports? Evidence from Machine Learning and Textual AnalysisMandatory Pollution Abatement, Environmental Awareness, and Firm Investment Why do US Firms use more Long-term Debt Post Activist Interventions?1、How Have Stock Markets Responded to 35 Years of Analyst Reports? Evidence from Machine Learning and Textual AnalysisWorking paper, issued in July 2019.Abena Owusu, Rensselaer Polytechnic InstituteAbstractUsing machine learning (ML) and contrasting with simple textual sentimentscore and principal components analysis (PCA) methods, we examine the time se-ries of content within over 700,000 sell-side analyst research reports from 1983 to2017. We find that analyst reports have significantly changed across a variety ofdimensions including length and content of four existing and two
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