Athenahealth, a Watertown, Mass.-based provider of cloud-based practice-management and electronic health-record system software and services, signed a definitive agreement to acquire Healthcare Data Services.

Financial terms of the deal were not disclosed, according to a spokesman for Athenahealth.

Healthcare Data Services is a Boston-based company that provides data analysis and population health management for payers and providers. Athenahealth said in a news release announcing the acquisition that the transaction is expected to strengthen its efforts to support healthcare organizations as they use risk-based payment models.

"With HDS, we can help healthcare organizations to thrive in the face of change—to drive down costs through smart, high-quality care coordination and to understand the totality of services being provided," Athenahealth Chairman and CEO Jonathan Bush said in the release. "This acquisition supports our existing efforts to create an information backbone that makes healthcare work as it should."

The deal is expected to close in October. Athenahealth was co-founded by current federal Chief Technology Officer and former HHS CTO Todd Park.