I just checked the six-channel view (see the post right above yours) so I know that Bloomberg is the other channel that gets added. MSNBC is always there, even in the four-channel view, as far as I know. The remaining channel in the four-channel view is C-SPAN, if I remember correctly. So, this seems to confirm my theory about the six-channel view, adding financial-themed channels during the day in order to track the stock market. Then, it switches to four of the main news channels for prime time.