Standard & Poor's put Tupperware Brands Corp. on watch for a possible ratings upgrade on Monday, saying the maker of plastic storage containers and makeup improved its operating performance in 2009.

Although sales declined last year, the company's margins expanded, mostly because of improved product mix and lower raw material and freight costs, Standard & Poor's credit analyst Christopher Johnson said.

Johnson said the better operating performance boosted cash flow and allowed Tupperware repay about $140 million in debt.

The ratings watch means S&P could affirm or upgrade the company after it completes its review. S&P also said the company made significant debt prepayments last year, improving its credit measures.

The rating agency has a "BB+" corporate credit rating on the company, which is its highest junk rating. S&P said the ratings reflect the risks of the company's direct-sales distribution model and its modest position in the highly competitive cosmetics industry.

As of Dec. 26, 2009, Tupperware had about $428 million in outstanding debt, S&P said.

Shares of Tupperware rose 15 cents to close at $45.71.