Technological Obsolescence
利用专利数据构建技术过时指标，发现技术过时预示企业增长、生产率和资本再配置显著下降，且高过时企业年收益率比低过时企业低7%，源于分析师高估其未来利润。
Abstract This paper proposes a new measure of technological obsolescence using detailed patent data. The measure contains incremental information about firm innovation relative to measures focusing on new innovation. Using this measure, we present two sets of results. First, firms’ technological obsolescence foreshadows substantially lower growth, productivity, and reallocation of capital. This finding mainly applies to obsolescence of core innovation and embodied innovation, and it is stronger in competitive product markets. Second, in stock markets, high-obsolescence firms underperform low-obsolescence firms by 7% annually. Using analyst forecast data, we show this is due to a systematic overestimation of future profits of obsolescent firms.