Advertisers have shunned San Francisco Giants slugger Barry Bonds. But his record-breaking 756th home run at AT&T Park on Tuesday has given millions of dollars in free advertising to a few lucky firms, including Stockton-based Diamond Foods Inc.

Diamond's shelled walnut sign is one of a handful of business ads that appear in footage of Bond's historic hit over AT&T Park's centerfield fence.

The video is destined to become part of baseball lore, giving companies whose brands appear in the 10-second snippet -- Diamond, Visa USA, Bank of America Corp., Charles Schwab Corp. and Kragen Auto Parts -- perpetual marketing exposure.

"We had hoped for weeks that this would happen," said Andrew Burke, Diamond's senior vice president of marketing. "Now we're waiting to see if we show up in Sports Illustrated -- not that we're getting greedy."

Burke wouldn't disclose how much Diamond pays to sponsor the Giants, but it gained $5 million to $6 million in free advertising for the day after Bonds' home run, according to Joyce Julius & Associates Inc. The Ann Arbor, Mich., firm tracks brand exposure on TV newscasts, sports and entertainment programs, then calculates what it would cost to buy enough ads to get the same impact.

"We're in uncharted territory here," said Joyce Julius research director Eric Wright. "This is something that was shown on every news and sports show in the country. It's just a few seconds, but this is total exposure for those four or five brands."

Kragen was the biggest winner. The company's logo was on a rotating board behind Bonds for several seconds before he homered on a 3-2 pitch from the Washington Nationals' Mike Bacsik. It was Bonds' 756th home run and broke a record that had stood for 33 years.

"Talk about luck," Wright said. "Usually a company gets between $13,000 and $13,500 worth of exposure from behind the plate. But Kragen's four seconds is hard to value. It's once in a lifetime."

For all of the corporate excitement over Bonds record-breaking performance, it's not likely to do much for his personal marketability. The slugger has been tainted by a steroids scandal and is the subject of a federal grand jury perjury probe.

"No sponsor wants him on their team," said Jason Michelotti with The Marketing Arm, a Dallas-based sports and entertainment promotions firm. "The risk of what could come down later outweighs the possible reward,"

San Francisco Baseball Associates LP owns the Giants and AT&T Park. The team usually folds signage deals into larger sponsorship packages, said Giants corporate marketing executive Mario Alioto.

Despite low expectations for the Giants going into the season and the team's last-place record so far, Bonds' home run record chase fueled excitement among the team's 100 corporate backers this season...