Analyst upgrades, downgrades and initiations: GLW, A, BHP, MJN, AET ...

Analyst upgrades:

Citigroup upgraded shares of Corning (NYSE: GLW) to Buy from Hold as it believes LCD glass production and sales have bottomed and will pick-up in Q2. The firm raised its target price to $16 from $11.25.
Thomas Weisel upgraded Celera (NASDAQ: CRA) to Overweight from Market Weight based on valuation and its strong business model.
ThinkEquity upgraded Varian Semi (NASDAQ: VARI) to Buy from Accumulate and raised its target to $32 from $20 based on valuation and weakness at its sole competitor.
Sanofi-Aventis (NYSE: SNY) was upgraded to Hold from Underperform at Jefferies.
Agilent (NYSE: A) was raised to Outperform from Neutral at Credit Suisse.
Liberty Interactive (NASDAQ: LINTA) was upgraded at JP Morgan to Neutral from Underweight.

Analyst downgrades:

Credit Suisse downgraded BHP Billiton (NYSE: BHP) to Underperform from Neutral on valuation as it sees risk of underperformance following the stock's recent outperformance.
Oppenheimer cut Harris (NYSE: HRS) to Perform from Outperform as it sees limited near-term upside due to the company's diminishing RF backlog. The firm lowered its target price to $35 from $60.
Deutsche Bank downgraded Cerner (NASDAQ: CERN) to Hold from Buy on valuation as it finds the risk/reward balanced at current levels. The firm lowered its price target to $43 from $46.
Stewart (NYSE: STC) was lowered to Market Perform from Outperform at Keefe Bruyette.
Coca-Cola Femsa (NYSE: KOF) was downgraded at Morgan Stanley to Equal Weight from Overweight.
AutoZone (NYSE: AZO) was downgraded to Neutral from Buy at UBS.

Analyst initiations:

Citigroup initiated Mead Johnson (NYSE: MJN) with a Buy rating and $32 target. The firm believes developing markets represent a significant opportunity for the company.
Leerink started Aetna (NYSE: AET) with an Outperform rating and prefers the company in the managed care group due to the company's execution and limited Medicare exposure. The firm has a 12-month valuation range of $30-$34.
Leerink is concerned about WellPoint's (NYSE: WLP) ability to respond to new cost trend developments given acquisition integration issues and inpatient unit-cost challenges. The firm has a 12-month valuation range of $35-$40 on the stock and initiated shares with an Underperform rating.
Exterran (NYSE: EXH) coverage was resumed with a Market Perform rating at Wachovia.