Standard & Poor’s Ratings Services has increased the counterparty credit ratings of 4 large health carriers.

Standard & Poor’s, New York, has increased the credit rating of CIGNA Corp., Philadelphia, to BBB plus, from BBB; of Health Care Service Corp., Chicago, to AA minus, from A plus; of Health Net Inc., Woodland Hills, Calif., to BB plus, from BB; and of Coventry Health Care Inc., Bethesda, Md., to BBB, from BBB minus.

The performance of all of those companies has been improving, Standard & Poor’s says.

The rating agency notes that it has concerns about Coventry’s strategy of growing through acquisitions.

The new Coventry rating is based on the assumption that Coventry will grow through relatively small acquisitions this year rather than completing a large-scale deal, Standard & Poor’s says.