Marsh McLennan

Marsh places commercial insurance for companies, and Guy Carpenter places reinsurance for insurers. Mercer advises on health and retirement benefits, and Oliver Wyman is the consulting arm, so a client can meet the group as a broker and as an advisor.

The broker of record letter gives Marsh the authority to market a program to Chubb, AIG, Travelers, and the rest. Switching brokers means a new letter, a new submission, and a loss of the incumbent's knowledge of last year's claims, which is why the relationship outlasts any one policy.

Reinsurance placement through Guy Carpenter is similarly concentrated, with Aon and Gallagher as the main alternatives. Contingent compensation and placement practices are part of how brokers are paid, and clients depend on disclosure of those arrangements when they compare brokers.

Broker-of-record appointments concentrate a client's market access in one intermediary.

Guy Carpenter's reinsurance placements sit between insurers and a short list of reinsurers.

Mercer benefits advice can steer an employer toward particular health and retirement vendors.

A risk manager who fires Marsh has to rebuild market relationships the broker held.

Insurers that rely on Guy Carpenter for catastrophe cover depend on that placement getting done before renewal.