Maryland Code, Insurance § 9-208

(1) an insurer that is doing or has done insurance business in the State and against whom claims arising from that insurance business may exist now or in the future;

(2) a person that purports to do insurance business in the State;

(3) an insurer that has insureds resident or located in the State;

(4) a person organized, or in the process of organizing, with intent to do insurance business in the State;

(5) a corporation that operates a nonprofit health service plan under Title 14, Subtitle 1 of this article; and

(6) a person that does, or has done, any of the acts of an insurance business specified in § 4-205 of this article.