Owner-level news-market concentration measures 1.30x higher than outlet-level measures

media-concentrationnews-ownershipantitrusthhi

Carragher and Carley (Carnegie Mellon, arXiv:2610.40164, submitted 29 Oct 2026) built a global news-ownership dataset — 9,761 domains, with reliable coverage in 77 countries — by linking digital news outlets to their ultimate corporate owners via Wikipedia/Wikidata, then cross-validated it against independent US (Medill) and UK (PINF) ownership directories and against Eli Noam's earlier cross-national census (entity-eli-noam; the paper reproduces his four-firm newspaper ranking at ρ=+0.465 and his HHI ranking at ρ=+0.407 across the 29–30 countries his 2008–2013 study covered).

Recomputing standard concentration indices — including HHI — at the owner level instead of the outlet level changes the measured answer: across the dataset's countries, owner-level concentration is a median factor of 1.30x higher than the equivalent outlet-level figure. Treating affiliated outlets (shared parent company, but separate mastheads or domains) as independent competitors therefore understates how concentrated a national digital-news market actually is. The gap is a methodological artifact of unit choice, not a claim about any single market or merger — it is the paper's baseline finding, which the rest of the paper's AI-citation results are then measured against at both levels.

Further verification

A single unrefereed preprint (no independent replication yet) underlies this and two sibling notes — see entity-herfindahl-hirschman-index for the shared methodology and question-corroborate-carragher-carley-2026-ai-overview-concentration-scenario for the fourth finding from this same source that the vault's single-source cap routed to the question queue instead of a claim-note.