1. In the stock trading system, the inventory quantity refers to the number of stocks that investors have traded. The number of securities refers to the number of stocks that have not yet been traded, including stocks entrusted to sell and stocks entrusted to buy but not yet traded. Therefore, the number of securities has been settled and transferred, and the settlement is carried out after the end of the day's trading. For example, if you just bought it today, there will be no transfer, so this part will not be included in the number of securities. As for the securities that were just sold today, they will still be shown in the number of securities because they have not been transferred. The inventory quantity shows the number of stocks you hold in real time, including those purchased on the same day but not transferred.

2. Securities are a general term for various economic rights and interests certificates, and also refer to specialized types of products. They are legal certificates used to prove certain specific rights and interests enjoyed by the ticket holder. It mainly includes capital securities, currency securities and commodity securities. Securities in a narrow sense mainly refer to securities products in the securities market, including equity market products such as stocks, debt market products such as bonds, and derivative market products such as stock futures, options, interest rate futures, etc. The discipline system of securities science is an organic system composed of various branches of disciplines that study the behavioral characteristics and operating rules of the securities market from different angles. It mainly includes two major research fields: traditional securities theory and evolutionary securities theory.