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.

NYSE Euronext

(NYX)

, the holding company for NYSE Group and Euronext, operates a group of exchanges. It has been upgraded to hold from sell. The company's third-quarter revenue rose by 96.9% compared with the same period last year, and that appears to have helped boost earnings. Its EPS rose to 97 cents a share compared with 43 cents per share in the third quarter of 2006.

NYSE Euronext's debt-to-equity ratio of 0.30 is below the industry average, implying that there has been very successful management of debt levels. However, the company's quick ratio of 0.39 demonstrates a lack of ability to pay short-term obligations. Its stock price has gone down by 4.48% in the last 12 months, and looking ahead, TheStreet.com Ratings does not see anything in the company's numbers that would change the one-year trend. NYSE Euronext had been rated a sell since coverage was initiated in April 2007.

Wesco Financial

(WSC) - Get Report

, through its subsidiaries, engages in the property and casualty insurance, furniture rental and steel service center businesses. It has been upgraded to a buy from a hold.

The company's debt-to-equity ratio of 0.02 is lower than the industry average, implying that there has been very successful management of debt. Wesco's third-quarter gross profit margin of 67.3% is rather high and has increased from the same quarter last year. Along with this, its net profit margin of 15.6% is above the industry average. The company's third-quarter earnings improved to $3.43 a share from $3.31 per share in the same period last year. These strengths outweigh the fact that the company's stock performance has been lackluster. Wesco had been rated a hold since July 2007.

Foundation Coal Holdings

( FCL) extracts, cleans and sells coal to electric utilities, steel companies, coal brokers and industrial users primarily in the U.S. It has been upgraded to hold from sell.

The company swung to a profit of $1.90 million in the third quarter from a loss of $10,000 in the same period last year, and while its revenue increased by 0.7% during that time frame, this growth rate trailed the industry average of 3.7%. Foundation Coal's stock price has gone up by 27.71% in the last 12 months, driving it to a price level that is now relatively expensive compared with the rest of its industry. Its reduced upside potential is not good enough to warrant further investment at this time.

The company's weaknesses include generally poor debt management, disappointing return on equity and poor profit margins. Foundation Coal had been rated a sell since coverage was initiated in February 2006.

PDL BioPharma

(PDLI) - Get Report

develops and commercializes therapies for severe or life-threatening illnesses. It has been downgraded to a sell from a hold.

The company's gross profit margin in the third quarter of 12.5% is extremely low, and it has decreased from the same period last year. PDL BioPharma's return on equity decreased in the third quarter when compared with the same period last year, and its revenue dropped 1.2% over the same time frame. The company's stock has fallen by 18.56% in the last 12 months, and the fact that the company is now selling for less than others in its industry in relation to its current earnings is not reason enough to justify a buy rating at this time. PDL BioPharma had been rated a hold since November 2006.

Knight Transportation

(KNX) - Get Report

provides truck transportation used primarily in short- and medium-length hauls. It has been downgraded to hold from buy.

The company has no debt to speak of, and it also shows a quick ratio of 2.38, which demonstrates the ability to cover short-term liquidity needs. Knight Transportation also shows good cash flow from operations. However, the company's third-quarter earnings fell to 17 cents a share from 22 cents per share in the same period last year. It also shows a disappointing return on equity.

The company's stock price has fallen by 3.89% in the last year, and the hold rating indicates that TheStreet.com Ratings does not advise purchasing shares right now. Knight Transportation had been rated a buy since December 2005.

Additional ratings changes are listed below.