Athenahealth shares fell sharply on Friday after the healthcare IT provider unexpectedly announced that CFO Kristi Matus had resigned in response to a change in its leadership structure.

Athenahealth said it was separating the roles of CFO and chief administrative officer, both of which had been Matus’ responsibility since she joined the company in July 2014. Her resignation becomes effective on May 31 and current vice president and controller Karl Stubelis will replace her as finance chief.

“Due to the bifurcation of her two primary areas of responsibility, Kristi Matus … has decided to leave Athenahealth to pursue new challenges,” Athenahealth said in a news release.

Kristi Matus

Analysts said the bifurcation could be viewed as a demotion for Matus, who was well-liked in the investment community. In trading Friday, Athenahealth stock dropped as much as 7.6% before rebounding slightly to close at $123.14, down 4.7% on the day.

Matus’ “departure may be indicative of internal operational challenges,” Leerink analyst David Larsen wrote.

Athenahealth provides cloud-based software and other services that help medical practices and hospitals collect payments from patients, manage their electronic health records, and automate their interactions with facilities like laboratories and radiology centers.

Before her move to Athenahealth, Matus was an executive at Aetna and United Services Automobile Association. “Kristi has been a valuable member of the management team and a key contributor to our growth through the one billion dollar revenue ceiling,” Athenahealth CEO Jonathan Bush said.

Stubelis has been with the company since 2013 and served as acting CFO before Matus’ appointment. He previously spent nearly a decade in finance leadership roles at Sapient Corp.

“Karl has been instrumental in modernizing our finance infrastructure to allow us to efficiently operate as a larger company,” Bush said. “His experience working with growth companies and multi-billion dollar revenue enterprises positions him extremely well to support our continued growth and operations as a maturing business.”