Recently, the legislator amending the Act of 15.09.2000 Kodeks spółek handlowych (Commercial Companies Code) (Journal of Laws of 2019, item 505, as amended), introduced a new, previously unknown type of company with share capital — a simple joint-stock company. When regulating it, among others the documentary form of shares was abandoned and the digitization of recording of shares (including their turnover) in the register of shareholders was provided for. Keeping the register of a simple joint-stock company was also enabled for notaries and the principle of constitutionality of entries made therein was introduced. However, new solutions in this area cannot be considered as encouraging to trading security. The purpose of the article is to draw attention to the fundamental doubts raised by the new regulation, in particular in the aspect of its impact on the activities of notaries performing activities related to keeping registers of shareholders of simple joint-stock companies.