資訊揭露制度於公司治理和證券市場均佔有不可或缺之地位。就我國現行關於重大訊息揭露之規範而言，規範不一致、相互矛盾之情況所在多有，且有混淆重大訊息之成立和揭露時點之現象，就併購訊息之揭露，除以特定時點作為揭露義務之啟動會產生過於僵化和易於操作之弊外，尚有過度傾向保護併購參與公司利益之嫌，使得重大訊息繼續性、即時性資訊揭露制度之成效不彰，而有揭露時點過晚之現象。因此，本文主張應將訊息之成立時點和揭露時點分別判斷，前者應著重於重大性，後者則應著重於實質明確性。就實質明確性之判斷，本文嘗試以盡職調查評估程序作為評估之切入點，就併購進行時雙方之協商程度、已就併購重要之點達成之結果和公司內部人或大股東對於併購案之影響力等要素加以綜合判斷，以併購之進行已達到實質明確性作為揭露之時點，並以盡職調查評估程序完成後之時點作為併購訊息揭露之最後底線，以避免法院進行實質判斷可能產生失之過狹或過廣的問題。

Information disclosure is essential to the corporate governance and security market. With regard to the regulations of material information ongoing or current disclosure, this article argues they not only are disordered and contradictory but confuse the timing of material information’ s establishment and disclosure. Focusing on the regulations concerning information disclosure of M&A, we find these kinds of regulations are rigid and easy to manipulate when the timing of disclosure is stipulated in a fact or occurrence in the specific time. Moreover, the effect of the regulations will overly incline to the interest of the companies involved in M&A and harm the interest of investors and shareholders that the system of information disclosure should protect, all of which give rise to procrastination of the M&A information disclosure as well as difficult implementation of the ongoing or current disclosure.To sum up, this article argues that it is necessary to distinguish the timing of material information establishment and disclosure. Furthermore, the former should focus on the determination of "materiality" while the latter should put emphasis on the determination of "substantial certainty". To be more specific, this article tries to use the effect of due diligence process, which is a key procedure taking a complete look at all the relevant sources of value and risk, to ascertain the timing of disclosure. Without attempting to catalog all such possible factors, we note the following may serve as indicia: actual negotiations between principals or their intermediaries, agreement in principle as to price and structure, the influence of insiders or majority shareholders to the transaction and so on. Therefore, this article argues that if the negotiation between participants of M&A transaction is reach the degree of "substantial certainty", the participants should immediately disclose the material information regarding the M&A transaction and cannot wait until the passage of a resolution by the board of directors. In order to avoid the situation of over inclusive or under-inclusive, this article tries to set the deadline of M&A information disclosure as the end of due diligence process.