Who hosts the FTSE 100?
Ask who hosts a company's website and the honest answer, for most of the FTSE 100, is: Cloudflare. Not because Cloudflare runs the application — in almost every case the real origin server sits behind it, on AWS, on Azure, on a managed hosting platform, or on the company's own infrastructure — but because the first hop a browser makes, and the IP address that resolves publicly, belongs to Cloudflare's edge network.
We resolved the primary website hostname for every FTSE 100 constituent we've crawled and looked up the announcing ASN — the internet's routing-registry record of which network operator owns a given IP range. It's a passive lookup: a DNS-shaped query against a public routing-registry mirror, not a scan of the target.
The top networks
| Network | Companies |
|---|---|
| Cloudflare, Inc. | 37 |
| Microsoft Corporation | 8 |
| Incapsula (Imperva) | 7 |
| Amazon.com, Inc. | 6 |
| Akamai (combined ASNs) | 10 |
Add Akamai's two announcing ASNs together and the picture sharpens further: the two biggest reverse-proxy/CDN vendors, Cloudflare and Akamai, front 47 of 75 FTSE 100 sites we've measured — considerably more than half. Incapsula (now part of Imperva) accounts for another 7, almost all of it web-application-firewall protection rather than plain CDN.
Why this concentration happens
None of this is really about hosting capacity — Cloudflare's free and low tiers cover a huge share of it, and a FTSE 100 company's actual compute almost never runs on Cloudflare's own servers. What a reverse proxy in front of a corporate site actually buys is DDoS absorption, a web application firewall, and TLS termination without an in-house team having to run any of it. For a company whose core business isn't running web infrastructure — which is most of the FTSE 100 — that's a rational trade, not a red flag. Concentration risk is still concentration risk, though: at that scale, a Cloudflare-wide outage or misconfiguration doesn't take down one company's website, it takes down a meaningful fraction of Britain's largest listed companies' public-facing presence simultaneously. That's happened before, industry-wide, more than once.
Full rankings — hosting, mail, DNS, and domain registrars together — at infrastructure analysis.