Analyst upgrades, downgrades and initiations: AMZN, LEAP, BBY, BANF, JBLU

Analyst upgrades:

JP Morgan upgraded shares of Amazon (NASDAQ:AMZN) to Overweight from Neutral as they believe the company's market share gains in the e-commerce sector will continue and that new product lines are adding diversification of revenue streams.
Wachovia upgraded Leap Wireless (NASDAQ:LEAP) to Outperform from Market Perform citing new market launches that should drive subscriber growth and reduced ARPU deterioration.
Deutsche Bank upgraded shares of Pride International (NYSE:PDE) to Buy from Hold as they believe investors will view the stock as a pure deepwater play beginning in Q2.
PDL BioPharma (NASDAQ:PDLI) was upgraded to Neutral from Underweight at JP Morgan.
Best Buy (NYSE:BBY) was raised to Buy from Neutral at Goldman.
Altera (NYSE:ALTR) was upgraded at Wachovia to Outperform from Market Perform.

Analyst downgrades:

Keefe Bruyette downgraded Southside Bancshares (NASDAQ:SBSI), Prosperity Bancshares (NASDAQ:PRSP), Cullen/Frost (NYSE:CFR) and BancFirst (NASDAQ:BANF) to Underperform from Market Perform on valuation and the weakening economic outlook in the Southwest.
Oppenheimer cut Varian Medial (NYSE:VAR) to Perform from Outperform as they believe U.S. hospitals could reduce capital spending budgets by 15%-25% in 2009.
Dress Barn (NASDAQ:DBRN) was lowered to Neutral from Buy at SunTrust based on valuation and lack of near-term catalysts.
JetBlue (NASDAQ:JBLU) was downgraded at Jesup & Lamont to Hold from Buy.
Credit Suisse cut Novellus (NASDAQ:NVLS) to Underperform from Neutral.
Helen of Troy (NASDAQ:HELE) was downgraded to Underweight from Neutral at JP Morgan.

Analyst initiations:

Merriman initiated Capstone Turbine (NASDAQ:CPST) with a Neutral rating and finds the stock fairly valued at current levels.
Leerink sees a high likelihood that Momenta's (NASDAQ:MNTA) lead product candidates M-Enoxaparin and M-356 clear regulatory and legal hurdles. The firm has an Outperform rating and $16 fair value estimate on shares.
NCI (NASDAQ:NCIT) was initiated with a Market Perform rating at Wachovia based on valuation.
Teradyne (NYSE:TER) was assumed at Barclays with an Overweight rating and $6 target.