AJGArthur J. Gallagher & Co.

Arthur J. Gallagher is an insurance broker grown through hundreds of acquisitions of small regional agencies.

The strategy differs from competitors' by the scale of consolidation: the company steadily buys small brokerages, folds them into a common platform and extracts better terms from insurers on aggregate volume. This is work with mid-market businesses rather than the largest corporations.

Commission is proportional to the premium, so rising insurance prices automatically raise income. Mid-market clients change broker less often than large ones, which makes revenue especially durable.

Risks: continuing to find acquisition targets at sensible prices, integrating dozens of deals a year, and a softening insurance market. The company pays a dividend with a long record of increases.