The x86 License DuopolyWide moat

At the base of AMD's whole business is a legal and structural fact of enormous value: only AMD and Intel possess the licenses to build x86 processors. The x86 architecture and its 64-bit extension (which AMD itself invented) are protected by a thicket of patents and cross-licenses that the two companies hold and that no third party can obtain. Since essentially all Windows PCs and most of the world's servers run x86 software, this makes AMD and Intel the only two suppliers of the processors at the heart of mainstream computing — a duopoly enforced not by market dynamics but by intellectual property.

This is the single most durable piece of AMD's moat, and it is what distinguishes the company's CPU business from an ordinary competitive market. A newcomer cannot enter: however much capital or talent it brought, it could not legally build an x86 chip, and building a non-x86 chip means confronting the vast installed base of x86 software that would have to be ported or emulated. The license is why AMD survived its near-death years intact and why, when its engineering recovered, there was a large, defensible market waiting for it to reclaim. It is a narrow moat's widest plank — but it is a duopoly shared with a larger rival, not an exclusive franchise — the cross-license binds AMD and Intel alone¹ — and the architecture it protects now faces its first serious challenge from Arm.