分析師不發佈研究報告亦具資訊意涵，本研究欲探討分析師停止發佈研究報告之企業，其未來績效是否與分析師預期一致，表現會較差，並進一步研究分析師停止發佈報告之預測正確性，是否會因分析師自身特性以及企業特性，影響分析師之預測正確性。研究期長為2007至2016年，發現分析師停止追蹤時，其當期股票之未來累積異常報酬卻較分析師持續追蹤或新增追蹤為高，但長期企業未來累積異常報酬較低，分析師具長期擇股能力。而在分析師特性方面，預測準確度較高的分析師能力較佳，其停止追蹤股票之未來累積異常報酬，相較於預測準確度低分析師之停止追蹤股票為低。在企業特性方面，當企業具有較高EPS波動性，因企業的未來不確定性高，降低分析師的預測能力，致較高EPS波動性公司的股票之未來累積異常報酬較低EPS波動性公司為高；當企業被較多的分析師追蹤時，因企業的資訊披露越高，致被較多分析師追蹤公司的未來累積異常報酬相較於較少分析師追蹤的公司為低。但若改採分析師的經驗作為分析師能力的代理變數，或以無形資產、廣告費用與研發費用作為企業特性變數，實證結果則不顯著。

The purpose of this paper is to examine whether the abnormal returns of stocks will be lower, when analysts decide to stop coverage. We assume that it also has the informationness when analysts do not publish reports. We also examine what analyst and firm characteristics will affect the validity of analyst forecast. The research period is from 2007 to 2016. We find that the cumulative abnormal return of stock is higher when the analyst stop coverage in the first year, but the long-term cumulative abnormal return is lower. We also find that analyst's forecasts are less valid for firms with higher EPS volatility because of higher uncertainty. Due to the information disclosure, analyst's forecasts are more valid for firms with more analyst coverage.

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