CNBC topped MSNBC and Headline News on Tuesday in Total Viewers, as investors watched the stock market tumble. CNBC had a total day (3a-3a) average of 401K viewers to HLN's 350K and MSNBC's 334K (Live +SD). The two news networks did beat CNBC in A25-54 viewers, however. The grid shows how the five cable networks fared in total day Tuesday. Nielsen does not yet permit FBN to release overnight data.

Other notes:
• In business day (5a-7p) CNBC averaged 469K Total Viewers, its best day since Sept. 17, 2001, the day the markets re-opened after the 9/11 attacks.

• CNBC averaged 642K Total Viewers during market hours (9:30am — 4pmET), also best since 9/17/01.

• CNBC's highest rated show for the day in the A25-54 demo was Deal or No Deal (269K viewers.)

• Squawk Box scratched in Total Viewers and A25-54 at 5amET and 6amET (5am: 45,000 T.V. / 18,000 A25-54) (6am: 101,000 T.V. / 47,000 A25-54.) Correction: Worldwide Exchange (not Squawk Box) airs at 5amET.