TheStreet.com Ratings: Stock Upgrades, Downgrades

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

While our 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 forecasted company earnings. Objective elements include volatility of past operating revenue, financial strength and company cash flows.

Some recent rating changes are highlighted below.

Building materials supplier Builders FirstSource(BLDR Quote) has been upgraded to a hold from a sell. TheStreet.com Ratings feels this company's major strength is its reasonable valuation level when compared to its peers. The price-to-earnings ratio for Builders FirstSource's stock is around half the industry average. The company had been rated a sell since July 2006.

Foodservice supplier Performance Food Group(PFGC Quote) has been upgraded to a buy from a hold. The company has demonstrated a pattern of positive earnings per share growth over the past two years. Net operating cash flow reached $20.8 million in the fourth quarter of fiscal 2006, a 51.2% jump from the same quarter a year ago. Performance Food Group had been rated a hold since July 2006.