CHICAGO (MarketWatch) -- Almost 40 million people watched Sen. Barack Obama's acceptance of the Democratic presidential nomination on Thursday night, according to Nielsen Media Research. That figure, which includes both broadcast and cable networks, is nearly twice the four-day average of the 2004 Democratic National Convention. And with 7.6 million black viewers, the event was the fifth most-watched nonsports program among African-Americans in 11 years, Nielsen added.