The paper presents a detailed overview of changes in capital equity in a joint-stock company, as the most important element of any capital company, including a joint-stock company itself. The specificity of a joint-stock company as a capital company is that its shareholders participate in dividing the capital equity into shares. Capital equity is an accounting category that can only be changed in specific cases. In the business books it is booked under the company's liabilities side, while the company's assets side is booked under assets. The paper explains in detail the role of capital equity. A joint-stock company can accumulate capital by internal or external way of financing. As the volume of business increases, so does the company's need for new capital. The reasons for the increase and decrease in capital equity can be found in the economic sphere. The capital equity is increased in order to raise new capital to finance the company's future business ventures. Some of the reasons may be the replacement of a certain debt with a share in the company, internal redistribution of capital so that certain shareholders goals regarding the 70 dividend payment policy can be achieved, possible takeover defense strategies, etc. In practice, this way of raising capital is becoming more common because it allows the creation of sources of financing without borrowing, and at the same time allows the company to pay off its liabilities and fulfill its needs required by daily business operations. Unlike the increase in capital equity, which is made in order to obtain new capital, the reduction of capital equity is not made only when the company has too much capital, which is rare. There can be other reasons, such as covering business losses. Part of the company's assets are subject to strict rules on the maintenance, or that can be one of the steps in future reorganisation of the company. The capital equity can be reduced in order to restructure the company, so that the increase of that capital is carried out together with it.