After the dematerialization of securities,the legal nexus of securities has changed greatly.The legal nexus of dematerialized securities can be summarized as "four subjects and three legal nexuses ".The legal nexuses between investors and issuers are different because of different holdings.The legal nexus between issuers and registration agencies is a kind of registration nexus,and between investors and registration agencies is deposit nexus.With the emergence of the Central Securities Depository,securities registration and securities depositories are in the gradual convergence.In general the relationship between investors and securities brokers is a kind of civil agency nexus whose contents are decided by legal agreements of the parties and the provisions of relevant laws,regulations and other normative documents.