According to a staff memo Monday from NBC News President Deborah Turness, she and Jamie Horowitz decided that, in her words, it "was not the right fit."
Horowitz started in September as senior vice-president and general manager of "Today." It was once the network morning show leader but has fallen behind ABC's "Good Morning America."
In her memo to staff, Turness says Horowitz would be replaced in "due course" and she will help oversee the show in the meantime.
NBC News declined to comment on Horowitz's departure.
Horowitz was president of original programming and production at ESPN. His TV career started with an entry-level position on NBC's Olympics team.