Stock Upgrades, Downgrades From TheStreet.com Ratings

Each weekday, TheStreet.com Ratings updates its ratings on the stocks it covers. The proprietary ratings model projects a stock's total return potential over a 12-month period, including both price appreciation and dividends. Buy, hold or sell ratings designate how the Ratings group expects these stocks to perform against a general benchmark of the equities market and interest rates.

While the ratings model is quantitative, it uses both subjective and objective elements. For instance, subjective elements include expected equities market returns, future interest rates, implied industry outlook and company earnings forecasts. Objective elements include volatility of past operating revenue, financial strength and company cash flows.

TheStreet.com Ratings has initiated coverage of the credit card company MasterCard(MA Quote) with a sell rating. The company's return on equity has fallen to just 5.3% in the first quarter of 2007, which is well below the industry average of 20.3%. In spite of this, the stock price is up 245% over the past 12 months. As a result, MasterCard now trades at a significant premium to its peers.

Medical-equipment manufacturer Cantel(CMN Quote) has been downgraded to hold from buy. The company provides products that help prevent and control infections. Net income was off nearly 51% in the third quarter of fiscal 2007 compared with the year-earlier period. Return on equity was also down, and at 4.7% it significantly trails the industry average of 23.9%. Cantel had been rated a buy since May 2007.