Insurers of all types watched their premiums and assets fall in 2008, with American International Group Inc. (AIG) a notable example, according to an analysis by A.M. Best Co.

A few insurers, including Berkshire Hathaway Inc. (BRKA, BRKB) bucked that trend in a big way.

Property/casualty insurers overall earned $444.06 billion in premiums in 2008, down 2.3% from the year before. Among the 200 largest by premiums earned, the picture was slightly better: Premiums were $419.99 billion, down 1.9%.

Among the top 10 insurers, AIG's property/casualty business took the biggest drop as premiums fell 9.4% to $31.95 billion in the year. AIG has been under pressure from competitors seeking to gain business as it struggles with fallout from its financial bailout.

Berkshire Hathaway, the company run by investment legend Warren Buffett, was the biggest gainer as premiums in its property/casualty business rose 12% to $21.52 billion.

Although many of the largest insurers sell both life and property/casualty insurance, they typically operate separate life and property/casualty insurance companies with premiums and assets reported separately for each.

A.M. Best ranks life and health insurers by admitted assets, which are used to determine statutory solvency. Life and health insurers' admitted assets dropped 8.8% in 2008, to $4.63 trillion.

According to the Insurance Information Institute, an insurer group, only assets that can be easily sold or borrowed against, and receivables for which payment is anticipated, can be included in admitted assets.

Total admitted assets fell 21% to $208.21 billion at fourth-largest Hartford Financial Services Group Inc.'s (HIG) life insurance business. It was the biggest drop of the top 10 life and health insurers. Hartford, which has struggled in the financial downturn, has said it would accept a government investment through the Troubled Asset Relief Program.

None of the 10 largest life insurers increased admitted assets in the year. Of the top 20, they rose for just one: The 18th-ranked Aflac Corp.'s (AFL) life insurance business, which reported a 29% increase, to $71.99 billion. The next best performance in the top 20 was by TIAA Group, fifth largest, which reported a 0.7% drop in admitted assets to $197.87 billion.

-By Lavonne Kuykendall, Dow Jones Newswires; (312) 750 4141; lavonne.kuykendall@dowjones.com