Half of largest 20 US public insurers saw market caps tumble in Q3

Ten of the top 20 largest U.S.-listed insurers recorded declines in market capitalization during the third quarter, according to an S&P Global Market Intelligence analysis.

Managed care giants Cigna Corp., Centene Corp. and Humana Inc. logged the biggest quarterly decreases in market capitalization for the period. Cigna's market capitalization decreased 16.3% to $68.08 billion. Centene's market capitalization dropped 14.5% to $36.33 billion and Humana's decreased 12.4% to $50.01 billion.

American International Group Inc. was the biggest gainer in the third quarter with a 14.9% increase to $46.94 billion. CFRA Research analyst Cathy Seifert previously told S&P Global Market Intelligence that AIG will be watched closely by investors as it is undertaking a major restructuring effort, one that includes a strategic alliance with Blackstone Inc.

The top four insurers by market capitalization remained unchanged in the period. UnitedHealth Group Inc. is still far and away the largest U.S. insurer by market capitalization despite a 2.5% quarter-over-quarter decrease. It finished the third quarter with a market cap of $368.44 billion.

MetLife Inc. leapfrogged its peers and jumped to fifth from seventh place in the third quarter following a 1% increase to $52.90 billion.

The S&P 500 Insurance Index rose almost 6.4% during the quarter, outpacing the broader S&P 500, which ticked up about 1.8%.