MOST NOTEWORTHY:

• Prudential upgraded shares of MGM Mirage (NYSE: MGM) to Overweight from Neutral on valuation, as the firm believes the recent weakness presents a buying opportunity.

• USA Truck Inc (NASDAQ: USAK) was raised to Equal Weight from Underweight at Stephens based on valuation.

• Jefferies upgraded shares of Knightsbridge Tankers Ltd (NASDAQ: VLCCF) to Hold from Underperform to reflect the company's five vessels now operating on long-term time charter contracts and its recent entry into the dry bulk shipping sector.

• Monolithic Power (NASDAQ: MPWR) was upgraded to Buy from Hold at Deutsche Bank following its patent win case against O2Micro International Ltd (OIIM).

• Wachovia upgraded Stanley Inc (NYSE: SXE) to Outperform from Market Perform based on its strong Q4 report and guidance...

• Cognos Inc (NASDAQ: COGN) was upgraded to Outperform from Sector Perform at Pacific Crest.

• Riverbed Technology, Inc (NASDAQ: RVBD) was raised to Overweight from Market Weight at Thomas Weisel.

• Stifel upgraded Priceline.com Inc (NASDAQ: PCLN) to Buy from Hold.

• Barrington raised X-Rite, Inc (NASDAQ: XRIT) To Outperform from Market Perform.

• Morgan Stanley raised Principal Financial Group Inc (NYSE: PFG) to Equal Weight from Underweight.

Analyst upgrades 5-17-07: COGN, PCLN and MGM originally appeared on BloggingStocks on Thu, 17 May 2007 10:36:00 EST. Please see our terms for use of feeds.