The proposed CVS Health-Aetna megamerger will reduce health-care costs for consumers immediately, the CEOs of both companies told CNBC on Monday. CVS Health CEO Larry Merlo and Aetna Chairman and CEO Mark Bertolini spoke on CNBC's "Squawk Box" Monday, one day after announcing that CVS will acquire Aetna for roughly $69 billion in cash and stock. The deal would combine CVS' pharmacy business and pharmacy benefit manager platform, also referred to as a PBM, with Aetna's insurance business. Upon closing, "they'll be things we'll be able to do out of the gate," Merlo told CNBC. "Over the next couple of years, you'll see a dramatic change in terms of the store not just being about products but also service offerings that can help people on their path to better health." CVS plans to run Aetna as a separate business unit. Bertolini will be on the combined company's board but won't be in charge of Aetna unit. The CEOs say they've had a business elationship since 2010. Merlo said he and Bertolini wanted to create a health-care platform that's "easier to use and less expensive for users." "It's really the perfect time," he said. "We have the ability to begin to bend that cost curve and at the same time help people achieve their best health."