Analyst upgrades:

• Citigroup upgraded Adtran (NASDAQ: ADTN) to Buy from Hold on expectations the company will benefit from the broadband Stimulus funds.
• Morgan Stanley upgraded Continental Airlines (NYSE: CAL) to Overweight from Equal Weight based on relative valuation and views the company as a "survivor." Additionally, the analyst lowered 2009 industry estimates but believes it is the last cut for the year and is incrementally more positive on the sector.
• Morgan Stanley also upgraded EXFO Electro-Optical (NASDAQ: EXFO) to Overweight from Market Weight based on valuation.
• Tata Motors (NYSE: TTM) was upgraded to Buy from Hold at Deutsche Bank.
• Ascent Solar (NASDAQ: ASTI) was upgraded to Neutral from Underweight at JP Morgan.
• Mechel Steel (NYSE: MTL) was upgraded to Neutral from Underperform at Credit Suisse.

MOST NOTEWORTHY: Trina Solar, Adtran and Elan Corp were today's noteworthy upgrades:

• Friedman Billings upgraded Trina Solar (NYSE: TSL) to Market Perform from Underperform citing expectations for improved FCF following the company's announcement to discontinue its in-house poly manufacturing.
  
• Thomas Weisel believes Adtran (NASDAQ: ADTN) is in a multi-year transition where new products are able to offset continued declines in the legacy products. Shares were raised to Overweight from Market WEight, and also upgraded at Raymond James to Strong Buy from Outperform.
  
• Goldman upgraded shares of Elan Corp. (NYSE: ELN) to Buy from Neutral to reflect their outlook for Tysabri and Bapineuzumab.

OTHER UPGRADES:

• Suntrust upgraded BOK Financial (NASDAQ: BOKF) to Buy from Neutral.
  
• Plains All American (NYSE: PAA) was upgraded at Morgan Stanley to Overweight from Equal Weight.
  
• Morgan Keegan upgraded Diodes (NASDAQ: DIOD) to Outperform from Market Perform.

MOST NOTEWORTHY: Nike Inc (NYSE: NKE), Foot Locker Inc (NYSE: FL), Tellabs Inc (NASDAQ: TLAB), ADTRAN, Inc (NASDAQ: ADTN) and Bookham, Inc (NASDAQ: BKHM) were today's noteworthy downgrades:

• Banc of America downgraded shares of both Nike and Foot Locker to Neutral from Buy, as the firm believes industry pressures in the U.S. could more than offset the potential turn in Europe and benefit from the 2008 Olympics.
• Cowen downgraded shares of ADTRAN, Bookham and Tellabs to Neutral from Outperform.
• Goldman Sachs also downgraded shares of Tellabs, to Sell from Neutral, as the firm believes the stock fully discounts the expected sales and margin improvement.

OTHER DOWNGRADES:

• Allergan Inc (NYSE: AGN) was downgraded to Equal Weight from Overweight at Morgan Stanley citing limited upside.
• Friedman Billings removed The Cheesecake Factory Incorporated (NASDAQ: CAKE) from its Top Picks and maintained its Outperform rating.
• Lehman downgraded shares of The First American Corporation (NYSE: FAF) to Equal-Weight from Overweight on increasing risk to the company's title margin and regulatory concerns.
• Matrix USA downgraded shares of Lowe's Companies Inc (NYSE: LOW) to Buy from Strong Buy on valuation.

When it comes to making the critical connections between a communications service provider and an end-user, you want to get your equipment from a manufacturer which grew up with the industry. At 22 years of age, there is a Huntsville, Alabama outfit that can claim to be a real grandfather in the field.

Adtran, Inc. (NASDAQ: ADTN) is a leading provider of networking and communications equipment, with a portfolio of more than 1,600 devices for use in the last mile of today's telecommunications networks. Widely deployed by both carriers and enterprises, the firm's systems enable voice, data, video, and Internet communications across copper, fiber, and wireless network infrastructures. Customers include Verizon Communications (NYSE: VZ), AT&T (NYSE: T) and Sprint Nextel (NYSE: S).

The company surprised the Street last week, when it reported Q1 EPS of 22 cents and revenues of $110.3 million. Analysts had been looking for 20 cents and $105.9 million. Management expected gross margins in the high end of the 50-60% range, going forward. The CEO attributed success to strength in High Data Rate Digital Subscriber Line demand, improving broadband access trends and ongoing momentum in inter-networking products. He anticipated further solid results, on the basis of new business wins and new product launches. ADTN shares popped on the news and are now forming a bullish "flag" consolidation pattern. Prices frequently exit flags moving in the same direction they were traveling when they entered them. In this case, that would be to the upside.

MOST NOTEWORTHY: Pfizer Inc (PFE), Exxon Mobil Corp (XOM), ConocoPhillips (COP), Xerox Corp (XRX), and Amazon.com, Inc (AMZN) were some of today's noteworthy downgrades:

• Prudential downgraded shares of Pfizer Inc (NYSE: PFE) to Neutral from Overweight with a $29 target to reflect concerns about competition from generic medications and a lack of new products.

• Deutsche Bank cut both ExxonMobil Corp (NYSE: XOM) and ConocoPhillips (NYSE: COP) to Hold from Buy on valuation.

• Citigroup downgraded shares of Xerox Corp (NYSE: XRX) to Sell from Hold as the firm believes the acquisition of Global Systems could hurt profits in the short-term. The broker recommended trimming positions of Xerox on any strength.

• Amazon.com (NASDAQ: AMZN) was cut to Underperform from Market Perform at Piper Jaffray based on valuation...

OTHER DOWNGRADES:

• Stifel lowered its rating of Jones Soda Co (NASDAQ: JSDA) to Hold from Buy on valuation.

• Deutsche Bank downgraded shares of Chevron Corp (NYSE: CVX) to Sell from Hold based on valuation.

• CIBC downgraded shares of Coventry Health Care, Inc (NYSE: CVH) to Sector Performer from Outperformer on valuation.

• Needham downgraded Vertex Pharmaceuticals Inc (NASDAQ: VRTX) to Hold from Buy.

• Adtran, Inc (NASDAQ: ADTN) was cut to Sell from Hold at Brean Murray.

• JP Morgan removed Johnson Controls, Inc (NYSE: JCI) from its Focus List citing recent share strength.

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