⚠ Partners Are Concentrated and PowerfulHigh threat

The depth of Arista's hyperscaler partnerships is inseparable from their dangerous concentration: the same relationships that are a moat are also a reliance on a handful of enormously powerful buyers who hold the leverage. Microsoft alone was roughly 26% of 2025 revenue and Meta another 16%¹ — about 42% of the business from two customers — with the cloud and AI titans together near 48%. This is concentration of a severe kind: Arista's fortunes ride on the spending decisions, supplier choices, and strategies of a few giants, each large enough that a change in its behavior would move Arista materially. The partners are deep, but they are few, and they are far larger than Arista.

The power imbalance expresses itself continually. The titans negotiate aggressively on price, using their enormous volume and their ability to shift business to extract discounts — visible in Arista's recent gross-margin decline, attributed partly to larger customers receiving greater discounts. They multi-source to preserve leverage and resilience. They can slow their capital spending in a downturn or an AI digestion phase, shift volume to a competitor like Nvidia or Cisco, or pursue their own white-box and in-house networking — any of which would strike Arista's revenue and margins directly. And their sheer importance means Arista must keep winning them on merit every generation, on their terms as much as its own. Arista serves these customers superbly and its integration is deep, so the relationships are durable while it remains the best option, and the AI build-out is driving their spending up. But an investor must weigh that Arista's greatest asset is a concentrated dependence on a few powerful giants whose decisions it cannot control — the clearest reason the moat is narrow, and the risk that would hurt most if it materialized.