近幾年來，美國證管會（SEC）及國際會計準則委員會（IASB）陳述其對於非公認盈餘（non-GAAP Earnings）被廣泛使用感到疑慮，認為非公認盈餘相關的揭露規定並不明確，導致不同公司之間的非公認盈餘資訊不易比較，而這模糊性可能會影響財務報表的溝通性。監管信函為美國證管會用以核閱公司所上傳相關文件是否能遵循相關資訊揭露規定，故本研究檢視公司是否會因收到與非公認盈餘相關之監管信函而改善其資訊的可比較性。實證結果顯示，當公司收到與非公認盈餘相關的監管信函後，非公認盈餘的可比較性增加，而分析師盈餘預測誤差及盈餘預測之離散程度均降低。

As non-GAAP earnings are widely used, the SEC and IASB have expressed concerns about this phenomenon in recent years. They believe that the non-GAAP earnings may lack of comparability because of the unclear definition of non-GAAP disclosure. These vagueness can also influence the communication between information users and companies. Since the SEC uses comment letters to monitor the registrants' filing reports and whether these reports are compliant with SEC disclosure requirements, our research investigates whether those receiving the SEC comment letters would improve their comparability of non-GAAP earnings. Our empirical results suggest that after the company received non-GAAP related comment letters, the comparability of its non-GAAP earnings increases while the analysts' earnings forecast error and dispersion decrease.