GULFPORT — Mississippi Power president and CEO Anthony Topazi has been named executive vice president and chief operating officer of Southern Company.

It’s one of several new executive appointments in a management transition plan at Southern Company.

Topazi will have responsibility for Southern Company Generation, Southern Power and Southern Company Transmission.

Edward Day VI will succeed Topazi as president and CEO of Mississippi Power, which provides retail electric service to about 200,000 customers in southeast Mississippi.

Southern Company CEO David M. Ratcliffe, who has run the Southern Company as chairman, president, and CEO since 2004, and has worked there since 1971, will retire Dec. 1.

The company said on Tuesday that Thomas A. Fanning will be the company’s new CEO.