MOST NOTEWORTHY: The Mosaic Company (MOS), LivePerson (LPSN) and three U.S. refiners were today's noteworthy downgrades:

• Goldman cut The Mosaic Company (NYSE: MOS) to Neutral from Buy on valuation.

• Stephens downgraded shares of LivePerson Inc (NASDAQ: LPSN) to EqualWeight from Overweight citing execution risk associated with the Kasamba.com acquisition.

• Citigroup cut shares of Sunoco Inc (NYSE: SUN) to Hold from Buy and Tesoro Corp (NYSE: TSO) and Valero Energy Corp (NYSE: VLO) to Sell from Hold based on valuation...

OTHER DOWNGRADES:

• Bear Stearns cut Ventana Medical Systems (NASDAQ: VMSI) to Peer Perform from Outperform.

• Baird downgraded F5 Networks (NASDAQ: FFIV) to Neutral from Outperform.

• Nuvelo Inc (NASDAQ: NUVO) was cut to Market Perform from Outperform at William Blair.

• Keefe Bruyette downgraded shares of Cowen Group (NASDAQ: COWN) to Market Perform from Outperform.

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

MOST NOTEWORTHY: Nuvelo (NUVO) and the Asian Semiconductor sector were today's most notable downgrades:

• Nuvelo (NASDAQ:NUVO) was downgraded to Neutral from Buy at Oppenheimer and Sector Performer from Sector Outperformer at CIBC World Markets, both companies citing negative clinical data;
• additionally, Merrill Lynch downgraded the Semiconductor sector to Market Weight from Overweight,
  • specifically downgrading Chartered Semiconductor (NASDAQ:CHRT), Siliconware Precision Inds Ltd (NASDAQ:SPIL) and STATS ChipPAC (NASDAQ:STTS) to Neutral from Buy
  • and United Microelectronic (NYSE:UMC) to Sell from Neutral, citing valuation.

OTHER DOWNGRADES:

• JP Morgan downgraded Wendy's (NYSE:WEN) to Underweight from Neutral as they believe shares are already pricing in years of sales and earnings growth at a time when competition is intensifying; they are also concerned over Wendy's new breakfast roll-out.
• Jefferies downgraded Autodesk (NASDAQ:ADSK) to Hold from Buy citing valuation.
• Bank of America said there are risks to Federated Dept. (NYSE:FD) comps at MAY stores and downgraded the company to Neutral from Buy, with a $43 target.

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

MOST NOTEWORTHY: The Small Cap BioTech sector top today's small list of initiations.

• The Bank of America initiated five companies within the Small Cap BioTech sector:
• Myriad Genetics, Inc. (NASDAQ:MYGN), Array BioPharma, Inc. (NASDAQ:ARRY), Nuvelo, Inc. (NASDAQ:NUVO) and Keryx BioPharmaceuticals Inc (NASDAQ:KERX) with Buy ratings
• and Dendreon Corp (NASDAQ:DNDN) with a Neutral rating.

OTHER INITIATIONS:

• Fiserv, Inc. (NASDAQ:FISV) was resumed with a Market Perform at Wachovia on valuation
• and Century Casinos, Inc. (NASDAQ:CNTY) was initiated with a Hold at Morgan Joseph on valuation.

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