Changes in the media industry and company earnings have resulted in a number of upgrades and downgrades to newspaper, broadcast and internet communication stocks this week. Stock upgrades include Sirius XM Radio (SIRI), Scripps Networks Interactive (SNI), Time Warner (TWX), Grupo Televisa (TV) and Cablevision Systens (CVC). Stock downgrades include British Sky Broadcasting Group (BSY), Interpublic Group (IPG) and Morningstar (MORN).

Here’s a complete breakdown of the media stocks upgraded or downgraded last week in Louis Navellier’s proprietary stock ranking database, Portfolio Grader. Portfolio Grader uses a simple letter-based system for stock upgrades and downgrades, where A is “strong buy” and F is “strong sell.” All of these stock upgrades and stock downgrades are current as of May 3, 2010:

Stock Upgrades – CVC, CJR, GSOL, TV, JRN, LAMR, MEG, SNI, SIRI, TWX

Sirius XM Radio (SIRI) was upgraded from a B grade or a “Buy” in Portfolio Grader last week to an A grade or “Strong Buy” this week in anticipation of its May 4 earnings report. Sirius XM is a satellite radio provider that has seen its SIRI stock soar about 50% since April 1. With analysts expecting earnings to pretty much break even, a small profit from SIRI stock this week could bode well for the stock’s performance after earnings.

Time Warner Inc. (TWX) was upgraded from a C grade or “Hold” last week to a B grade or “Buy” this week in Louis Navellier’s stock database. TWX stock is also set to report earnings this week, on Wednesday May 5. Time Warner has seen at least 7 upwards revisions to earnings estimates in the last month, resulting in the stock upgrade.

Grupo Televisa (TV), together with its subsidiaries, operates as a media company in Mexico and elsewhere internationally with a focus on Spanish language television. TV stock was upgraded this week to a C grade or “Hold” from a D grade or “Sell” last week.

Cablevision (CVC), a regional television provider that serves 5 million households and businesses in the New York metropolitan area, saw its CVC stock upgraded this week from a B grade or a “Buy” in Portfolio Grader last week to an A grade or “Strong Buy” this week in anticipation of earnings. Cablevision reports earnings on Thursday, May 6.

Scripps Network Interactive (SNI) was upgraded from a C grade or “Hold” last week to a B grade or “Buy” this week in Louis Navellier’s stock database. in The SNI stock upgrade was in anticipation of earnings. Scripps Network Interactive also reports earnings on Thursday, May 6.

Stock Downgrades – ASCMA, BSY, IPG, MORN, WPPGY

Morningstar Inc. (MORN) was downgraded from a C grade or “Hold” to the worst grade in Portfolio Grader this week — F, or “Strong Sell.” Morningstar Inc. provides investment research. Market uncertainty in the wake of the Goldman Sachs scandal and oil spill in the Gulf of Mexico is weighing on retail investors and on MORN stock. This is why Morningstar was downgraded.

British Sky Broadcasting (BSY) provides pay television broadcast services in the United Kingdom and Ireland. BSY stock was downgraded this week to a C grade or “Hold” from a B grade or “Buy” last week.

Interpublic Group (IPG) provides advertising and marketing services worldwide. IPG stock reported poor earnings last week and was subsequently downgraded in Louis Navellier’s stock ranking database. The company fell from a C grade or “Hold” last week to a D grade or “Sell.”

About Portfolio Grader: Every Sunday, renowned growth stock adviser Louis Navellier runs a fundamental analysis on the top 5,000 Wall Street companies. Armed with this research, Navellier offers a rating for each company reflected as a simple letter grade, with A being “strong buy” and F being “strong sell.” Portfolio Grader’s stock data is free and open to the public, and can be accessed online here.