A stock ledger is the record of the shares held in a company. The stock ledger is also referred to as the register of members, the share register and the shareholder register (among others).
In many countries, it is a requirement that every company keeps a register of its shareholders. The information included in the stock ledger is the name and address of each shareholder, the quantity of shares owned by the shareholder, the class of shares held (=category of shares in which each share has the same voting rights, value, and characteristics), the amount paid for the shares, and the date on which the shareholder acquired the shares/ceased to be a shareholder.
It is important that the company regularly updates the stock ledger so that it accurately reflects current shareholders and their shareholdings. It is a requirement in many countries for the company to keep the stock ledger available for inspection at its registered office. This is useful to enable e.g. a person who wants to buy shares in the company to see who the other shareholders are and how many shares they own.