Health insurer Cigna buying Express Scripts for $52 billion

Health insurer Cigna is buying the nation's biggest pharmacy benefit manager, Express Scripts , the latest in a string of proposed tie-ups as health care's bill payers attempt to get a grip on rising costs.

The $52 billion deal announced Thursday follows the drugstore chain CVS Health Corp.'s roughly $69 billion bid to buy the insurer Aetna Inc., an acquisition the companies detailed in December.

Insurers and pharmacy benefit managers — which run drug plans for insurers and employer-based plans — have struggled to keep costs under control for clients like big companies that provide coverage to their workers.

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