Cognex -4.9% on valuation-driven Oppenheimer downgrade

• Citing valuation, Oppenheimer has downgraded Cognex (NASDAQ:CGNX) to Market Perform ahead of its May 4 Q1 report.
• The downgrade comes a day after the industrial machine vision hardware maker closed less than $2 below a 52-week high of $52.48. After rallying in February following a Q4 beat, shares trade for 35x 2015E EPS.