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

Commercial real estate services firm

CB Richard Ellis

(CBG)

has been downgraded to a hold from a buy. The company's net income fell 67.5% to just under $12 million in the first quarter of 2007 from $36.9 million for the same quarter last year.

TheStreet.com Ratings feels CB Richard Ellis' profit margins are poor. CBG had been rated a buy since December 2006.

Japanese wireless telecommunications provider

NTT DoCoMo

(DCM)

has also been downgraded to a hold from a buy. Despite growing revenue, the company's earnings per share tumbled 42.1% in the fourth quarter of 2006.

DCM's return on equity has decreased over the past fiscal year to just under 11%, well below the industry average. NTT DoCoMo had been rated a buy since February 2007.

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Rent-to-own business

Rent-A-Center

(RCII) - Get Rent-A-Center Inc Report

has been upgraded to a buy from a hold. TheStreet.com Ratings says revenue growth is this company's primary strength. Revenues jumped 24.4% in the first quarter of fiscal 2007 compared to the same quarter a year ago, much higher than the specialty retail industry average of 1.2% during the same time period.

Although Rent-A-Center has suffered a pattern of declining earnings per share over the past two years, analysts are looking for this trend to reverse in the future. RCII had been rated a hold since July 2006.

Fashion designer and retailer

Liz Claiborne

( LIZ) has been downgraded to a hold from a buy. Net income fell 65.5% in the first quarter of fiscal 2007 compared to the same quarter a year ago. The company's 10.4% return on equity is less than half the textiles, apparel and luxury industry average of 21.1%. Liz Claiborne had been rated a buy since April 2005.

Biotech firm

Cephalon

( CEPH) has been boosted to a buy from a hold. The company's earnings shot up dramatically over the past fiscal year, reaching 99 cents per share in the first quarter of fiscal 2007 compared with just 5 cents per share for the same quarter in 2006. TheStreet.com Ratings is expecting this trend of impressive EPS growth to continue.

Meanwhile, Cephalon's stock is still trading at a noticeable discount to its peers. CEPH shares have a price-to-earnings ratio of 25.7, far lower than the biotechnology industry average of 111.2. Cephalon had been rated a hold since February 2007.

Some recent rating changes are highlighted below.