Advertising money is moving online -- and away from TV. One small sign:

Fourth-ranked broadcaster NBC has quietly begun reimbursing advertisers an average of $500,000 each for failing to reach guaranteed ratings levels, the first time a network has taken such a step in years, media buyers said.

Networks usually offer make-goods -- free advertising slots -- in the event of such shortfalls. But NBC has none to give. ...

CBS, ABC and Fox also are doling out make-goods, primarily for the first quarter. They have blamed softness on a new ratings formula, but media agencies disagree. None of the networks would comment.

Update: Per Silicon Alley Insider:

• the original story is from Adweek
• the WSJ (subscription required) covered NBC's response