19 USC 2351 - Firm defined
For purposes of this part, the term firm includes an individual proprietorship, partnership, joint venture, association, corporation (including a development corporation), business trust, cooperative, trustee in bankruptcy, and receiver under decree of any court. A firm, together with any predecessor or successor firm, or any affiliated firm controlled or substantially beneficially owned by substantially the same persons, may be considered a single firm where necessary to prevent unjustifiable benefits.