Analyst upgrades:

• Wachovia upgraded shares of Exelon (NYSE: EXC) to Outperform from Market Perform to reflect the company's attractive nuclear fleets and strong operational track record.
  
• Jesup & Lamont upgraded Ormat Technologies Inc. (NYSE: ORA) to Buy from Hold on valuation and increasing visibility on near-term Products revenue.
  
• RBC Capital upgraded Memc Electronic (NYSE: WFR) to Outperform from Sector Perform on expectations of improved demand growth following the likely eight-year extension of the US solar tax credit program.
• AmBev (NYSE: ABV) was raised to Outperform from Neutral at Credit Suisse.
  
• AmerisourceBergen (NYSE: ABC) was upgraded at Merrill Lynch to Buy from Neutral.
  
• Piper upgraded Anadys Pharma (NASDAQ: ANDS) to Neutral from Sell.

Analyst downgrades:

MOST NOTEWORTHY: Burger King Holdings, Inc (BKC), Supertel Hospitality Inc (SPPR), OSI Pharmaceuticals, Inc (OSIP), Brown-Forman Corp (BF.B) and NGAS Resources, Inc (NGAS) were today's noteworthy initiations:

• CIBC considers shares of Burger King Holdings (NYSE: BKC) to still be attractive and has above-consensus estimates, starting shares with an Sector Outperformer rating. The firm believes increased operating hours and breakfast value meals will drive results, while cost savings should help margins.

• JMP Securities believes there is plenty of room for growth at Supertel Hospitality (NASDAQ: SPPR) via acquisitions, leading to strong FFO upside, initiating shares with an Outperform rating and $8 target.

• ThinkEquity sees additional upside for Tarceva and started OSI Pharmaceuticals (NASDAQ: OSIP) with a Buy rating and $50 target.

• AG Edwards believes Brown-Forman (NYSE: BF.B) is well-positioned to benefit from new trends in spirits and wine, starting shares with a Buy rating and $74 target.

• RBC Capital is positive on NGAS Resources' (NASDAQ: NGAS) growth potential and high quality assets, starting shares with an Outperform rating and $11 target...

OTHER INITIATIONS:

• CIT Group (NYSE: CIT) was started with a Market Perform rating at Keefe Bruyette.

• Oppenheimer started shares of Watsco, Inc (NYSE: WSO) with a Buy rating.

• ThinkEquity started Coley Pharmaceutical Group, Inc (NASDAQ: COLY) with an Accumulate rating and $10 target.

• Goldman initiated shares of Northwest Airlines Corp (OTC: NWACQ) with a Neutral rating and $26 target.

• Duetsche Bank initiated PPL Corp (NYSE: PPL) with a Buy rating and $51 target.

• Citigroup initiated Comverge, Inc (NASDAQ: COMV) with a Hold rating and $26 target.

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

MOST NOTEWORTHY: Chico's FAS, Inc (CHS), Live Nation (LYV) and Clear Channel Communications, Inc (CCU) were some of today's notable upgrades:

• Friedman, Billings, Ramsey upgraded shares of Chico's FAS Inc (NYSE: CHS) to Market Perform from Underperform and raised their target to $25 from $17 on valuation.

• Matrix USA upgraded Live Nation (NYSE: LYV) to Hold from Sell on valuation.

• Sanders Morris upgraded Clear Channel Communications (NYSE: CCU) to Hold from Sell, as the firm believes the disapproval by holders to sell the company will result in shares trading in the $34-$37 range.

OTHER UPGRADES:

• Lehman upgraded PPL Corp (NYSE: PPL) to Overweight from Equal-Weight.

• Friedman, Billings, Ramsey continued to recommend shares of Urban Outfitters, Inc (NASDAQ: URBN) with an Outperform rating as the firm has seen consistent progress at both the company's divisions throughout March. Friedman added Urban Outfitters to its Top Picks list.

• JP Morgan raised Sonic Corp (NASDAQ: SONC) to an Overweight rating from Neutral, and believes shares have priced in softer Q2 sales that were pre-announced late-February.

• Martha Stewart Living Omnimedia, Inc (NYSE: MSO) was upgraded at Bear Stearns to Peer Perform from Underperform.

• Morgan Stanley upgraded Mylan Laboratories (NYSE: MYL) to Neutral from Sell.

• Goldman Sachs upgraded the Mortgage Insurance sector to Neutral from Cautious.

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