Express Scripts says it has completed its $29.1 billion acquisition of Medco Health, creating the country's largest pharmacy benefits manager.

The closing comes after the Federal Trade Commission voted to close its investigation into the deal, clearing the last hurdle in its path.

The deal creates a company so large that it will handle the prescriptions of more than one in three Americans.

St. Louis-based Express Scripts Inc. says it still expects the deal to result in cost savings of $1 billion once Franklin Lakes, N.J.-based Medco Health Solutions Inc.'s operations are fully integrated into its own.