HCA Healthcare CEO R. Milton Johnson will retire at the end of the year and be replaced by veteran executive Sam Hazen, the hospital chain's president and chief operating officer.

The company also said Monday that Johnson will leave its board next spring and be replaced as chairman by Thomas F. Frist III.

HCA, based in Nashville, runs 178 hospitals and 119 surgery centers in several states and the United Kingdom. Johnson has served as CEO since 2014.

Hazen has been with HCA for nearly 36 years.

Leerink analyst Ana Gupte says Hazen is highly respected on Wall Street and a natural successor to Johnson.

Shares of HCA Healthcare Inc. slipped in early trading.