Mass. Gen. Laws ch. 164 § 85
The officers and employees of the department may be authorized by it to examine the books, contracts, records, documents and memoranda or the physical property of any company subject to this chapter, and of any affiliated company with respect to any relations, transactions or dealings, direct or indirect, between such affiliated company and any company so subject, and, for any examination so authorized, shall be entitled to full access to the subject matter thereof. No such officer or employee shall divulge any fact or information coming to his knowledge during the course of such an examination unless directed by the department or by the court, or authorized by law.
For the purposes of this section and of section seventy-six A, the words "affiliated company" shall include any corporation, society, trust, association, partnership or individual (a) controlling a company subject to this chapter, either directly, by ownership of a majority of its voting stock or of such minority thereof as to give it substantial control of such company, or indirectly, by ownership of such a majority or minority of the voting stock of another corporation or association so controlling such company; or (b) so controlled by a corporation, society, trust, association, partnership or individual controlling as aforesaid, directly or indirectly, a company subject to this chapter; or (c) standing in such a relation to a company subject to this chapter that there is an absence of equal bargaining power between the corporation, society, trust, association, partnership or individual and the company so subject, in respect to their dealings and transactions.
Mass. Gen. Laws ch. 164, § 85