Express Scripts revenue surged in the three months through September, even as speculation mounted that the Trump administration will try to revamp a key piece of its business model.

Sales at the pharmacy benefit manager, which earlier this year won federal approval for its merger with Cigna, grew to $25.6 billion. Profit rose 27 percent to $1.1 billion, or $1.89 a share.

"As we look ahead to our planned combination with Cigna, we will offer greater affordability and differentiation through our relentless focus on patient care, cost containment and continuous innovation," Chief Executive Officer Tim Wentworth said in a statement. Executives expect the transaction to be completed by the end of the year.

Because of the pending merger, Express Scripts didn't hold a call for investors, as is customary after quarterly earnings. The company's stock was flat in after-hours trading in New York.

The Trump administration is expected to take aim at the current drug rebate system, under which benefit managers like Express Scripts receive a portion of the discount they negotiate with drug companies. The industry has pushed back against allegations the rebates lead to higher drug prices, with CVS Health’s top executive calling the claim “entirely false.”

Competition between the benefit managers "means more and more rebates are going, and will continue to go, back to clients,” Chief Executive Officer Larry Menlo told investors in August.