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 June 23. IHS ( IHS) -- which provides critical information and decision-support tools to customers in the energy, defense, aerospace, construction and electronics industries -- has been upgraded to buy. IHS' revenue growth has slightly outpaced the industry average of 27%. Quarterly revenue grew 34% over a year ago. During the past fiscal year, IHS increased its bottom line by earning $1.39 a share vs. $1.03 in the prior year. This year, the market expects an improvement in earnings ($1.93 vs. $1.39). Its net income increased by 25% when compared to the same quarter one year prior, rising from $18.58 million to $23.26 million. Net operating cash flow has increased to $62.49 million, or 46% when compared with the same quarter last year. In addition, IHS has also modestly surpassed the industry average cash-flow growth rate of 40%. We feel that the stock's sharp appreciation over the last year has driven it to a price level that is now somewhat expensive compared with the rest of its industry. The other strengths this company shows, however, justify the higher price levels. IHS had been rated a hold since May 2008.