We have analyzed the content and described the procedure of a special legal instrument used in course of issuable securities placement within the framework of reorganization, i.e. stocks conversion procedure. We have considered its influence on the equity capital structure of legal successors. We found out that stocks conversion procedure is a sequence of actions aimed at the determination of securities’ quantity to be issued to every shareholder in place of cancelled stocks of the legal predecessor using a specific stocks conversion ratio. Differences in the stocks conversion procedure are related to stocks conversion, as to whether every share shall be converted separately, or just a certain set of shares which shall be subject to conversion. We have described three types of candidate procedures aimed at determination of securities quantity to be placed to a shareholder while using the stocks conversion method. We formulated mathematical model for every algorithm. We analyzed the stocks conversion procedure under conditions of cross-shareholding by shareholders of a company under reorganization. The proposed method enables us to determine the real participation interest under the actual control of certain shareholders in the context of their indirect participation in equity capitals by virtue of other legal bodies. Nowadays, it is a very pressing problem to reveal the real dependence and affiliation of the participants in the economic turnover.