Net income for the health insurance industry declined 12.4 percent as of Sept. 30, compared to the same period last year, according to analysis by Highline Data, which provides financial and marketing information on insurance companies.

Net income for the industry totaled $8.2 billion. According to Highline Data, more than a third of health companies reported underwriting losses in the third quarter, with larger market players considerably outperforming their smaller competitors. Thirty-five percent ($2.8 billion) of total industry net income in the first nine months of the year was earned by the top 1 percent of companies ranked by 2008 total assets.

Underwriting costs, which primarily include health benefit payments, increased by 6.9 percent year-over-year and totaled $332 billion as of Sept 30. Underwriting costs showed a five-year CAGR of 9.5 percent, outpacing total revenue, which showed a five-year CAGR of 9.2 percent.