Three quarters of regulated financial services depend on one vendor ecosystem.
We extend the governance topology framework outward, to cross-institutional dependencies through shared vendor relationships. A single technology vendor ecosystem is present across 414 of 543 regulated financial institutions. The concentration generates 85,491 pairwise cross-institutional links through that ecosystem alone. A governance event at the dominant vendor reaches three quarters of the regulated population simultaneously, not sequentially. Under DORA Article 28, each institution manages its vendor relationship bilaterally. No regulatory framework monitors the aggregate cross-institutional surface.
Each bar measures the share of 543 regulated financial institutions that deploy at least one AI agent through the named vendor group. Hyperscaler A is the dominant ecosystem comprising the major cloud platform and its associated foundation model partner. Hyperscalers C and B are the second and third cloud platforms. Foundation Model B is an independent foundation model provider. Enterprise Vendor A is a long-established enterprise technology supplier. The penetration of Hyperscaler A exceeds the next-ranked vendor group by a factor of 2.9. The cross-institutional dependency surface this generates is structurally invisible to bilateral vendor risk assessment under DORA Article 28.