The Washington Post said Sunday that its executive editor, Sally Buzbee, has stepped down after three years at the top of one of journalism’s most storied brands.

She will be replaced by Matt Murray, former editor in chief of The Wall Street Journal, through this fall’s presidential election. Following that, Robert Winnett, deputy editor of the Telegraph Media Group, will take over as editor as the newsroom restructures its operations.

No reason was given for Buzbee’s departure. She…