Specialization by business class or region continues to distinguish insurers with the best long-term combined ratio averages on National Underwriter's second-ever ranking of property-casualty insurance profit leaders. This year, however, a different set of specialists top our list, highlighting the growth of some of the smallest competitors, the volatility of p-c underwriting results, and the sensitivity of our rankings to combined ratio results of the last two years.

In our Jan. 24, 2005, edition, we presented our inaugural "Profit Leaders" analysis, using information generated by NU corporate subsidiary Highline Insurance Data to rank carriers based on the arithmetic average of the combined ratios they recorded over the six years extending from 1998 through 2003. We assigned the highest rankings to those with the lowest six-year averages.

This year, we repeat the same analysis, updating the combined ratio averages to reflect the most recent full six years available: 2000 through 2005. While 12 insurance organizations made a repeat appearance among the top-25 profit leaders, 13 newcomers pushed some of last year's leaders out of the top ranks.