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. Celestica ( CLS) provides electronic manufacturing services and solutions to original equipment manufacturers in the communications, computing, industrial and consumer sectors in Asia, the Americas and Europe. It has been upgraded to a hold from a sell. The company's net income swung to a profit of $51.5 million in the third quarter from a loss of $42.1 million in the same period last year. Celestica's debt-to-equity ratio of 0.35 is below the industry average, implying that there has been successful management of debt levels. However, the company's gross profit margin is low, at 7.30%. Its stock price has dropped 43.02% in the last 12 months, as investors have so far failed to pay much attention to the EPS improvements over the last quarter. While the stock is now cheaper (in proportion to earnings over the past year) than most other stocks in its industry, due to other concerns, TheStreet.com Ratings feels the stock is still not a good buy right now. Celestica had been rated a sell since October 2005. Operating through five segments, The Thomson Corporation ( TOC) provides information and services to business and professional customers. It has been upgraded to a buy from a hold. The company's revenue grew by 11% in the third quarter compared with the same period last year, outpacing the industry average of 8.3%. Thomson's debt-to-equity ratio of 0.28 is below that of the industry average, implying that there has been successful debt management. Its stock price has increased by 9.88% over the past 12 months, and while any stock can fall in an overall down market, it still has good upside potential. The company's earnings increased to 50 cents a share in the third period compared with 32 cents a share for the same period last year. Stable earnings over the past year indicate that the company has sound management over its earnings and share float. Thomson had been rated a hold since September 2007, prior to which it had been rated a buy since October 2005.