$19.1 billion Cigna Corporation, one of the largest U.S. health insurers, has announced that Chief Accounting Officer Annmarie Hagan has been promoted to the role of chief financial officer, effective immediately.

Hagan has served as Cigna's chief accounting officer since 2001. She also took on the additional role last year of controller, overseeing financial and management reporting, financial planning and analysis, and expense management.

Hagan assumes the post from former CFO Mike Bell, who is leaving after 25 years at the health insurer. Bell has served as CFO since 2002.

Cigna has not yet named a replacement for Hagan's roles.