Campbell Soup's S&P ratings unaffected by buyback

Before the market opened, Campbell's said its board of directors authorized the buyback program to go through the end of the company's 2011 fiscal year.

S&P said it expects Campbell's to "maintain a prudent financial policy and stable credit measures."

"If credit measures weaken, the company cannot meet our benchmarks, and/or the company pursues a more aggressive financial policy, we could revise the outlook to 'Negative,' " the ratings agency said.

Campbell Soup's shares rose $1.82, or 5.7 percent, to $34 in afternoon trading.