Analyst upgrades:

• Citigroup upgraded Advanced Micro (NYSE: AMD) to Buy from Hold and raised its target to $5.50 from $4.25 citing valuation and expectations for the company's competitive position and gross margins to improve.
• Barclays upgraded American Express (NYSE: AXP) to Overweight from Equal Weight citing long-term earnings growth as the company benefits from declining charge-offs and credit costs. The firm has a $38 target on the stock.
• JPMorgan upgraded Arch Coal (NYSE: ACI) to Overweight from Neutral and raised its target to $22 from $19 citing the FTC approval for the acquisition of Jacobs Ranch mine and valuation.
• Bebe Stores (NASDAQ: BEBE) was upgraded to Overweight from Equal Weight at Stephens.
• Cheesecake Factory (NASDAQ: CAKE) was upgraded to Neutral from Underweight at Piper Jaffray.
• Ashland (NYSE: ASH) was upgraded to Buy from Hold at KeyBanc.

MOST NOTEWORTHY: Luminent Mortgage (LUM), JetBlue (JBLU), Thornburg Morgtage (TMA) and Harmony Gold (HMY) were today's noteworthy downgrades:

• Luminent Mortgage (NYSE: LUM) was downgraded by a host of firms following suspension of its dividend and 10Q filing delay:
  
• UBS cut shares to Sell from Neutral.
  
• Deutsche Bank downgraded Luminent to Sell from Buy.
  
• Friedman Billings and JMP Securities downgraded shares to Underperform from Market Perform. Keefe Bruyette downgraded Luminent to Market Perform from Outperform.

• Morgan Stanley downgraded JetBlue (NASDAQ: JBLU) to Underweight from Equal Weight based on expected competition from Virgin American and their stretched balance sheet.

• Deutsche Bank downgraded shares of Thornburg Mortgage (NYSE: TMA) to Sell from Hold telling accounts it does not believe REIT taxable earnings will be able to support the dividend.

• Deutsche Bank and UBS cut shares of Harmony Gold (NYSE: HMY) to Sell from Neutral after the company lowered its earnings forecast and the CEO resigned...

OTHER DOWNGRADES:

• Thomas Weisel downgraded F5 Networks (NASDAQ: FFIV) to Market Weight from Overweight.

• AG Edwards cut Nuveen Investments (NYSE: JNC) to Sell from Hold.

• Pali Capital downgraded Clearwire (NASDAQ: CLWR) to Neutral from Buy.

• Matrix USA downgraded PPG Industries (NYSE: PPG) to Buy from Strong Buy.

• Wachovia cut U-Store It Trust (NYSE: YSI) to Underperform from Market Perform.

Analyst summaries provided by TheFlyOnTheWall.com (subscription required).