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 May 14. AVX Corp. ( AVX), which manufactures passive electronic components and related products, has been upgraded to buy. For the fourth quarter, revenue grew 7% year over year to $405.9 million, while earnings per share declined to 21 cents from 25 cents. For 2008, the market is expecting a contraction in full-year EPS to 86 cents from 88 cents in 2007. Gross profit margin is rather low at 18%. At 8.8%, net profit margin exceeds the industry average. Shares have fallen 28% in the past year, netting the stock a price-to-earnings ratio of 14.95, which places it at a discount to others in its industry. AVX Corp. had been rated hold since March 18.