One of the most successful corporate structures for long-term shareholder returns has been an insurer whose float is invested by a capable capital allocator. While Warren Buffett's Berkshire Hathaway (BRK.B) is the largest and best-known example, its success has been matched at a smaller scale by companies like Markel (MKL) and Alleghany (Y). Buffett explains the benefits of float in his 2009 annual letter:
If premiums exceed the total of expenses and eventual losses, we register an underwriting profit that adds to the investment income produced from the