An amendment to the articles is a fundamental company change. In some states, relatively minor changes, such as changing the registered agent, may be made by the board without requiring approval from shareholders. While certain changes may involve reorganization of the company's structure.  These changes, referred to as "fundamental corporate changes," may be defined as modifications to a company that mandate a bylaw amendment, that is internal documents, and therefore require consent from shareholders who are parties to the contractual agreement outlined in the charter.

1. Why Would Anyone Want to Amend the Articles?
   
   Articles of Amendment are official legal instruments utilized to make changes—or amendments—to the original Articles of Incorporation filed with the state. They allow business owners to legally change certain aspects of their company, such as its name or the authorized share capital.
   
   In the event of a change in the company's operations that is inconsistent with the matters stated in the company's articles of incorporation, the company's articles of incorporation shall be amended.
   
   
2. Which Items of U.S. Company’s Article of Incorporation Can Be Amended?
   
   In the case of a corporation, the following aspects of the company can be modified:
   
   

   (1)	Modification of U.S. Company Name U.S. corporations are authorized and bound to use only their state registered name to operate, and any modification to this name necessitates obtaining approval from the state authorities to adopt the new name. A name change for a U.S. corporation needs to be made by filing an amendment to the articles of incorporation or an amendment to the organization and adopted by the corporation's board of directors unless its article provide for the name change to be adopted by the corporation's shareholders or members or managers.
   (2)	Increase the number of authorized shares The articles of incorporation must be amended if the corporation has issued all of the shares authorized in the original articles and the corporation wants to raise capital by issuing more shares.
   (3)	Modification of registered agent and address A registered agent is a person or entity responsible for representing a company in legal matters and documentation. A change of agent may be due to a variety of reasons, such as the departure of an agent, internal restructuring of the company, or a change in partnership. Before making a change of agent, the bylaw need to be prepared to confirm the legality of the change, and if the company has a board of directors, the board of directors needs to pass a resolution to confirm the change of agent. A company's registered address is the company's legal point of entry and an important basis for communication with government and other organizations. A change of registered address is necessary when a company relocates, expands or needs to better accommodate business needs. Amendments to the bylaw need to be made and signed along with the filing of the change of registered address document.
   (4)	Other modification in personnel involving the operation of a company Other changes in personnel involve the ownership or operation of a company, such as the directors/managers of a U.S. corporation. These changes can be accomplished by amending the article of incorporation, while the company's board of directors will need to pass a resolution to issue a director/manager appointment letter to be filed with the state or registrar to apply for the change.
   (5)	Modification of shareholders or owners of U.S. company If a U.S. company is registered with a “customized” article of incorporation that shows shareholder or owner information, it may be possible to change the names and addresses of the owners of the corporation as listed in the U.S. company's articles of incorporation.
   (6)	Add an exculpation clause to the articles If a U.S. company is incorporated with a "customized" article of incorporation that includes an exculpation clause, under the Model Business Corporation Act (MBCA) (2016), the articles may include a provision “eliminating or limiting the liability of a director to the corporation or its shareholders for money damages for any action taken, or any failure to take any action, as a director”. In every state, though, the right to exculpate through such provisions is limited. Under the MBCA (2016), exculpation is not permitted in cases involving: (a) Receipt of an improper financial benefit (b) Intentional infliction of harm on the corporation or shareholders (c) Approval of an unlawful distribution, or (d) Intentional violation of criminal law. Other states word the exceptions differently, but the upshot is similar everywhere: the articles can exculpate directors for liability for damages for breach of the duty of care, but not for breach of the duty of loyalty.

See also:
Types of U.S. Company Mergers

Reference:
[1] Richard D. Freer. The law of corporations in a nutshell. West Pub. Co, 2020.