Networks sell advertising time based principally on...

Networks sell advertising time based principally on their performance among key demographic groups, which vary based on the time of day. Ratings performance in these categories give a rough indication of network revenues in that period of day, though profitability can fluctuate based on programming costs and other factors.

Prime Time

Ratings for adults 18-49

NBC

Last week: 4.6

Season to date: 6.6

ABC

Last week: 3.5

Season to date: 5.2

Fox

Last week: 3.0

Season to date: 5.2

CBS

Last week: 2.7

Season to date: 4.2

UPN

Last week: 1.3

Season to date: 1.9

WB

Last week: 1.2

Season to date: 1.3

Size of group: 123,150,000

Note: Each rating point equals 1% of group

Sources: Nielsen Media Research, networks