Aon plc Class A Ordinary Shares (Ireland)

We assess multiple durable moats: 1) Switching costs 90/100, weight 30%: Mission‑critical risk placement, multi‑year programs and regulatory complexity yield mid‑90s retention rates, raising migration barriers. 2025 commentary confirmed retention improved by 50 bps to a mid‑90s rate. 2) Efficient scale 85/100, weight 25%: Global brokerage is an oligopoly where the top three brokers benefit from dense global footprints that deter new entrants. 3) Intangibles 85/100, weight 20%: Brand trust, regulatory know‑how, proprietary models like ReMetrica and PathWise, and the Aon Client Treaty facility underpin credibility with both clients and carriers. 4) Cost advantage 80/100, weight 15%: Aon Business Services centralizes operations and technology, enabling structural margin expansion and lower unit costs at scale. 5) Network effects 70/100, weight 10%: While not classic, there is a two‑sided scale dynamic between a large client base and carrier capacity that improves placement terms.

Weighted, these yield a strong composite moat. Evidence: retention and margin expansion in 2025, Client Treaty renewals, and ABS‑enabled efficiencies.