Each business day, 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. However, the rating does not incorporate all of the factors that can alter a stock's performance. For example, it doesn't always factor in recent corporate or industry events that could affect the stock price, nor does it include recent technology developments and competitive dynamics that may affect the company. For those reasons, we believe a rating alone cannot tell the whole story, and that it should be part of an investor's overall research. The following ratings changes were generated on September 16. BJ Services Company ( BJS) has been downgraded from buy to hold. BJ Services Company and its subsidiaries provide pressure pumping and oilfield services for the petroleum industry worldwide. Our recommendation is based on the company's double-digit revenue growth and impressive sales across all segments. These positive factors are strengthened by the company's healthy cash position, low leverage and positive management outlook. However, downside risks to the buy rating include less drilling activity in North America, fluctuating commodity prices, declining returns and lower margins.