What is the definition of an Alien Insurer?

An Alien Insurer is defined as a company that is headquartered outside the United States but is actively conducting business within the U.S. This term specifically refers to the geographical distinction of the insurer's home country relative to where it operates. By understanding this definition, one can appreciate the regulatory considerations that apply to such companies, including the need to comply with U.S. laws and regulations while continuing to adhere to the insurance laws of their home jurisdiction.

The other choices represent different types of insurers. A domestic insurer is one that is incorporated in the same state where it operates. Foreign insurers are those incorporated in a different state but doing business in the state in question, thus offering another layer of differentiation. Meanwhile, a company following state regulations for foreign insurers typically refers to how foreign companies need to adapt to local rules, but it does not define what an Alien Insurer is. Therefore, the correct option effectively captures the essence of what constitutes an Alien Insurer.