Anthem Inc., the No. 2 U.S. health insurer by membership, said medical spending rose in the second quarter, driven by higher costs from the insurer’s Affordable Care Act plans and Medicaid business.

The shares dropped as much as 4.1 percent, the biggest intraday decline since April 27, and were down 0.5 percent to $136.95 at 9:55 a.m. Anthem said it spent 84.2 cents of every premium dollar on medical care, up from 82.1 cents a year earlier.

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