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Serena's Outburst Might Have Cost Her

Serena Williams
AP
Serena Williams

The early read on Serena Williams' marketability following her outburst in the U.S. Open final was that she wouldn't be hurt in the endorsement world.

None of her sponsors - Nike , Gatorade and Kraft -- dropped her and a Tampax endorsement, signed before the Open, was even announced in the days after she was criticized for her behavior.

But a new poll exclusively released to CNBC.com by the Davie Brown Index, an index that measures a celebrity's ability to influence brand affinity and consumer purchase intent, shows Williams might have taken a hit.

Her appeal score, taken this week, dropped more than eight points, as compared to a poll taken in July. Her endorsement score dropped more than five points and her trust score dropped almost five points in the DBI Index.

The DBI's Chris Anderson said opinions certainly have changed, but it might be "because the image of her yelling at the line judge is still so fresh."

Anderson said about the same number shift happens, in a positive light, when a player wins an MVP award. But that doesn't mean Williams won't feel the affects of her actions for months, and maybe years, to come.

"It could have been over quickly if immediately after she said, 'Boy, I messed up,'" Anderson said. "But she didn't. It just continued on. And that what makes people upset. How long will they be upset for? We'll have to keep an eye on it."

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