The Marrow Market is GLMZ's primary black market for biological material — organs, tissue, blood, genetic material, and the increasingly valuable commodity of unaugmented biological samples in a city where finding a completely unmodified human is becoming rare. The Market operates as a brokerage rather than a direct-operation criminal organization: it connects sellers (desperate the Gray Zone residents willing to part with a kidney, chop shop operators with harvested organs, corrupt morgue workers with unclaimed bodies) with buyers (black market surgeons, pharmaceutical researchers, wealthy individuals seeking transplants outside the regulated system, and — most lucratively — biotech companies running research programs that require human biological material they can't obtain through legal channels).

The Market employs approximately 100 people: brokers who manage buyer-seller relationships, logistics specialists who transport biological material under conditions that maintain viability, quality assessors who verify material authenticity, and security personnel who protect a supply chain that many parties would like to disrupt or steal from. The operation is cold, efficient, and treats human biological material with the same dispassionate professionalism that a commodity exchange treats pork bellies.