Today was one of those days where many traders looked like and acted like they wanted to just lock in gains after what was the first full week for many traders in about three weeks. Yet shares stayed strong. Options expiration dates and a S&P rebalance brought in some added volatility and money managers are now scared to tell their clients that they are not all-in on stocks. So while markets were up most of the day, the real closing bell with all of today's events was something that felt as though it would be down to the wire.

Here were today's unofficial closing bell levels:

Dow 9,819.52 +35.60 (0.36%)
S&P 500 1,068.26 +2.77 (0.26%)
Nasdaq 2,132.86 +6.11 (0.29%)

Top Analyst Upgrades
Top Analyst Downgrades
Top Day Trader Stocks

Analyst upgrades:

• Wells Fargo transferred coverage of Cooper Industries (NYSE: CBE) with an Outperform rating, upgraded from the previous analysts' Market Perform rating. The firm believes commercial construction will be of less of a headwind for the company than the Street thinks, and has a $38-$41 valuation range on the stock.
• Kaufman Bros. upgraded SuccessFactors (NASDAQ: SFSF) to Buy from Hold after channel checks indicated demand trends picked up in July. The firm raised its target on shares to $15 from $12.
• UBS upgraded eBay (NASDAQ: EBAY) to Buy from Neutral and believes Marketplace transaction growth is "turning the corner." Additionally, the firm believes the secondary market represents a long-term opportunity for the company. The firm raised its target to $28 from $24.
• Novartis (NYSE: NVS) was upgraded to Buy from Hold at Jefferies.
• Arcelor Mittal (NYSE: MT) was upgraded to Buy from Hold at Citigroup.
• Cardinal Health (NYSE: CAH) was upgraded to Buy from Neutral at Goldman.
• Yahoo! (NASDAQ: YHOO) was upgraded to Outperform from Market Perform AMC Monday at Bernstein.

Analyst upgrades:

• Keefe Bruyette upgraded American Express (NYSE: AXP) to Outperform from Market Perform to reflect improving credit trends following the July monthly data. The firm raised its target price on shares to $37.
• Oppenheimer upgraded Corning (NYSE: GLW) to Outperform from Perform as it believes 2010 estimates are achievable and concerns over falling LCD demand are overdone. The firm set a $19 price target on the stock.
• JPMorgan upgraded International Game Technology (NYSE: IGT) to Overweight from Neutral on valuation and expectations domestic replacement orders will pick up. The firm has a $23 price target on shares.
• Goldman Sachs (NYSE: GS) was raised to Buy from Neutral at Pali Capital.
• Portland General Electric (NYSE: POR) was upgraded to Buy from Neutral at Goldman.
• Mechel Steel (NYSE: MTL) was upgraded to Neutral from Reduce at Nomura.

When a $7 a share biotechnology company like Dendreon Corp. (NASDAQ: DNDN) rockets 200% to over $20 a share in one day, like it did yesterday after reporting successful Phase 3 trials of its prostate cancer drug, investors get interested in any biotech stock under $10.

But before investing in these speculative companies, you should have a clear understanding of how this niche operates. Marketing plays an important role in order for the companies to raise capital, therefore if you are interested in betting on a company's future, you should consider the risk factors and odds of success.

MOST NOTEWORTHY: Arena Pharma, Windstream and StatoilHydro were today's noteworthy upgrades:

• Banc of America upgraded shares of Arena Pharma (NASDAQ:ARNA) to Buy from Neutral on valuation following the recent weakness and would-be buyers ahead of the Lorcaserin 12 month echocardiogram Data Safety Monitoring Committee review expected in March.
  
• Jefferies named Windstream (NYSE:WIN) their Tuesday Value Pick and upgraded shares to Buy from Hold, as they find the current valuation attractive and believe the company can improve operating results over the next 12 months through realization of acquisition synergies, cost cutting, top-line growth initiatives and additional M&A.
  
• Credit Suisse raised StatoilHydro (NYSE:STO) to Outperform from Neutral as they believe the company has addressed issues with growth and capital expenditure and set more conservative targets.

OTHER UPGRADES:

• JP Morgan added Applied Materials (NASDAQ:AMAT) to its Focus List.
  
• Bernstein upgraded the U.S. Life Insurance sector to Overweight from Market Weight and upgraded MetLife (MET) to Outperform from Market Perform.
  
• Citigroup upgraded M&T Bank (NYSE:MTB) to Hold from Sell.
  
• Goldman added Pride International (NYSE:PDE) to its Conviction Buy List.

MOST NOTEWORTHY: First Solar, JA Solar, Alcatel-Lucent, Nokia and Ericsson were today's noteworthy initiations:

• First Solar (NASDAQ: FSLR) and JA Solar Holdings (NASDAQ: JASO) were initiated with Buy ratings and targets of $160 and $61 at Collins Stewart. Collins Stewart sees room for margin expansion and is positive on First Solar after channel checks; the firm expects JA Solar to expand capacity given its long-term supply agreements with four wafer suppliers.
  
• Merrill Lynch started shares of Alcatel-Lucent (NYSE: ALU) with a Sell rating, citing a lack of revenue growth prospects.
  
• The firm also started shares of Nokia Corporation (NYSE: NOK) with a Buy rating, as they believe the company's share gains and margin expansion will continue.
  
• Merrill also resumed coverage of Ericsson (NASDAQ: ERIC) with a Neutral rating, expecting high single digit earnings and share growth, but not enough for a Buy rating.

OTHER INITIATIONS:

• Goldman initiated the trucking and railroad sectors with Neutral ratings.
  
• Wachovia initiated Isis Pharmaceuticals (NASDAQ: ISIS), BioMarin and Molecular Insight (NASDAQ: MIPI) with Outperform ratings and Bioenvision (NASDAQ: BIVN), Dendreon Corporation (NASDAQ: DNDN), Arena Pharmaceuticals (NASDAQ: ARNA) and Neurocrine Biosciences (NASDAQ: NBIX) with Market Perform ratings.

MOST NOTEWORTHY: The biotech sector, WESCO International, Wyndham and Century Casinos were today's noteworthy initiations:

• BMO Capital initiated coverage on Arena Pharmaceuticals Inc. (NASDAQ: ARNA) and Gilead Sciences Inc. (NASDAQ: GILD) with Outperform ratings and a $16 target and $51 target and Celgene Corp. (NASDAQ: CELG) and Genentech Inc. (NYSE: DNA) with Market Perform ratings and a $69 target and $85 target.
  
• CIBC initiated shares of WESCO International Inc. (NYSE: WCC) with a Sector Outperformer rating and $46 target. The firm believes lower estimates are already priced into shares and that the company's operating initiatives increase the chances for more stable margins in this environment.
  
• Deutsche Bank started shares of Wyndham Worldwide Corp. (NYSE: WYN) with a Buy rating and $41 target. The firm believes stability of the timeshare industry, international expansion and improved transparency will serve as catalysts for shares.
  
• Century Casinos Inc. (NASDAQ: CNTY) was initiated at Nollenberger with a Neutral rating, citing the underperformance of new properties and concerns from the smoking ban in Colorado; however, the firm believes the company is headed in the right direction.

OTHER INITIATIONS:

• Soleil started shares of Sunoco Inc. (NYSE: SUN) and Valero Energy Corp. (NYSE: VLO) with Buy ratings and targets of $96 and $88, and initiated shares of Tesoro Corp. (NYSE: TSO) with a Hold rating and $55 target.
  
• Rodman & Renshaw started shares of Labopharm Inc. (NASDAQ: DDSS) with a Market Perform rating.
  
• UBS resumed coverage on Kroger Co. (NYSE: KR) with a Buy rating and $34 target.

MAJOR PAPERS:

• According to people familiar with the matter, Home Depot Inc (NYSE: HD) was close to accepting about $1.2B less for the sale of its wholesale distribution business to three private-equity firms, but there was uncertainty about whether the deal would close by last night's deadline, reported the Wall Street Journal (subscription required).
• Ford Motor Company (NYSE: F) CEO Alan Mulally urged the Federal Reserve to stimulate the economy and focus on economic growth, reported the Financial Times (subscription required).

OTHER PAPERS:

• British energy company BP plc (NYSE: BP) is warning that a fierce environmental campaign may force it to scrap a $3.8B expansion at one of America's biggest oil refineries, reported the U.K. Times.
• From BusinessWeek's "Inside Wall Street" column:
  
• Spirits company Diageo plc (NYSE: DEO) may be the perfect tonic for jittery markets, and could appreciate 20% to 25% annually for several years, said Randy Haase of Baron Fifth Avenue Growth Fund.
  
• As household budgets get squeezed, consumers are likely to spend more at discount retailers - and TJX Companies Inc (NYSE: TJX), owner of T.J . Maxx, is one of the best bets.
• In September, Arena Pharmaceuticals Inc (NASDAQ: ARNA) will announce 6-month safety review for its lead drug, lorcaserin, an obesity drug, which is in a large phase III test.

MOST NOTEWORTHY: Hewlett-Packard Co (HPQ), Tekay Offshore Partners LP (TOO), Auxilium Pharmaceuticals, Inc (AUXL) and Northwest Airlines Corp (NWA) were today's more noteworthy initiations:

• Friedman Billings started Hewlett-Packard (NYSE: HPQ) with an Outperform rating and $53 target.

• Teekay Offshore (NYSE: TOO) was initiated with a Hold rating and $30 target by Deutsche Bank based on valuation.

• Banc of America noted that if approved, Auxilium Pharmaceuticals' (NASDAQ: AUXL) lead candidate, AA4500, could become a first-in-class therapy, with an over-$800M sales potential in niche markets, with no competition. Bank of America started AUXL with a Buy rating and $22 target.

• Northwest Airlines (OTC: NWACQ) was initiated at Morgan Stanley with an Equal Weight rating...

OTHER INITIATIONS:

• Banc of America assumed coverage of Gilead Sciences, Inc (NASDAQ: GILD) with a Buy rating and increased its target to $94 from $90. Banc of America also started Arena Pharmaceuticals, Inc (NASDAQ: ARNA), Amylin Pharmaceuticals, Inc (NASDAQ: AMLN) and Celgene Corp (NASDAQ: CELG) with Neutral ratings.

• Credit Suisse assumed coverage of RF Micro Devices, Inc (NASDAQ: RFMD) with an Outperform rating.

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

Arena Pharma (NYSE: ARNA) skewed option implied volatility suggests risk into Autumn review. ARNA, a clinical stage biopharmaceutical company focusing on G protein-coupled receptors (GPCRs), closed at $14.32. ARNA's Lorcaserin, a treatment for obesity, has a Date Safety Monitoring Board (DSMB) review in the autumn of 2007. Bank of America started coverage of ARNA with a Neutral rating and a $16 price target on 5/24. BAMO say's "we expect a positive DSMB review, which could provide significant short-term gains in the stock in late 2007." ARNA June option implied volatility is at 44, October at 90 and January is at 66 according to Track Data, suggesting larger risk this autumn.

United Rentals (NYSE: URI) volatility Flat as URI explores strategic alternatives. URI, the largest equipment rental company in the world, closed at $32.85. URI announced on 4/10/07 that it is exploring strategic alternatives. URI June option implied volatility of 33 is near its 26-week average according to Track Data, suggesting flat risk.

Daily Option Update is provided by Stock Options Specialist Paul Foster of theflyonthewall.com.

Cramer on tonight's MAD MONEY discussed his new favorite biotech play.

Cramer gave a backgrounder: he said on Jan 11 his Zymogenetics, Inc. (NASDAQ:ZGEN) pick is now up 15% and he still likes it. He also discussed Myogen, Inc. (NASDAQ:MYOG) because it is being acquired by Gilead Sciences, Inc. (NASDAQ:GILD) and he picked MYOG to be bought. He wanted to look for another Myogen.

Cramer has a new favorite name in biotech development is Arena Pharmaceuticals, Inc. (NASDAQ:ARNA). He said Arena has a weight loss drug in its pipeline, and it should be a huge revenue generator. He said it isn't just because of obesity, but people are (after all) fond of spending money to look good, and will take it for this purpose, too. He said this drug in Phase III does not have the side effects of the offerings from other obesity drug companies.

After Cramer discussed this it popped 7% after-hours, resulting in market capitalization of $603 million as of the $12.75 close. He did note ahead of his call not to trade it right after he discussed it in after-hours "because you'll get robbed."

Cramer was also positive on Amgen, Inc. (NASDAQ:AMGN) and Genentech, Inc. (NYSE:DNA).

Jon Ogg is a partner in 24/7 Wall St.; he does not own securities in any of the companies he covers.