The two want to create an integrated health system that combines pharmacy and health benefits while delivering preventive care services through the drugstore chain's retail clinics.
Last week, the DOJ asked the firms to provide more information on the proposed deal, just as the 30-day waiting period under the Hart Scott Rodino Act expired. But CVS CEO Larry Merlo said its original timetable built in that request and "things are moving along as planned."
"In addition, the integration planning just begun, and we have assembled a team with representatives from both companies and are very pleased with how the planning process is progressing," Merlo said on a call following the release of CVS' fourth-quarter results.
Shareholders are slated to vote on the deal on March 20.
CVS' stock fell about 5 percent and Aetna's dipped about 2 percent on Thursday.