I examine the properties of the circular equity investment that is the investment in the form of rings. At the first, I theoretically research how the circular equity investment affect to the ownership-control disparity of a business group. When the investment cycle is formed, cash flow rights , the ownership, of all affiliated firms are increased while the voting right, the control right, of only the last affiliate is increased and others' voting rights decrease. Therefore the circular equity investment raises the last affiliate's ownership-control disparity but decreases other affiliates' ones. I show that, because of this attribution, the circular equity investment has ambiguous effects on the ownership-control disparity in the business group level. Secondly, I point out that “fictional capital” is created not from the circular equity investment but from any equity investment. I show the empirical case that the fictional capital ratio of a business group with the simple M-form structure is greater than one of the business groups with circular investment structures.