The Associated Press has a good article on this subject, dated August 21.

"....A total of 33 Fox advertisers, including Walmart, CVS Caremark, Clorox and Sprint, directed that their commercials not air on Beck's show, according to the companies and ColorofChange.org, a group that promotes political action among blacks and launched a campaign to get advertisers to abandon him. That's more than a dozen more than were identified a week ago...."

It goes on to examine the dilemma of advertisers who are trying to reach the most eyeballs, but those programs tend to be the political opinion shows, whether liberal or conservative. They have the viewers, but they also can anger and alienate customers.

Link to the full article
Attack on Obama riles Beck's advertisers