One of the methods for extrinsic development of companies is the merger that can be arisen by a contract or law and can be simple or by formation of a new company (consolidation). In simple merger, one or more companies are absorbed by another company, but in consolidation, a new company is created by dissolution of some companies. Surviving or new company is general surrogate of the merged company or companies and as their surrogate can be sued by others. According to the unanimous decision of the Supreme Court No. 851 if a bank has multiple branches in different locations, claims arising from the obligations of each branch with third parties or shareholders must be filed in the local court in whose jurisdiction the branch is located. Therefore, when a bank merges with another bank, the branches of this bank are considered the successors of the merged bank or institution, and the trying claims by individuals falls within the jurisdiction of the court where the branch of that bank is located. However, the application of this decision is not reliable, and to determine the competent authority, one must pay attention to factors such as whether the company is listed or unlisted, whether it is public or private, etc. Therefore, if one or more listed companies merge into another listed company and the dispute arises from the professional activity of the merged company in the capital market, the arbitration board has the inherent jurisdiction to try it. Instead, if the merging or merged company, or both, is not listed on the stock exchange, or the lawsuit is not related to professional activity in the capital market, or it is a state-owned company and the lawsuit is for interest on securities, trying the lawsuit is within the inherent jurisdiction of the judiciary.