This ethnographic case study provides authentic insights into the intertextual negotiation processes for a particular merger-and-acquisition (M&A) transaction in the context of international legal practice, involving interdisciplinary legal and business professionals. Using genre and discourse analytical methodology, this study focuses on the interactional discourse practices and textual products used for negotiation of the primary sale and purchase agreement. By providing sociolinguistic insights into the M&A negotiation process, these research findings can promote a better understanding of the professional discourse activities and interactional role behaviors for this very important area of international business law practice.