Goldman Sachs analyst Brian Essex upgraded FireEye (FEYE) to Buy from Neutral with an unchanged price target of $18. The stock closed Wednesday up 89c to $13.89.

The recent decline in FireEye shares have been more pronounced than the average move across the sector, Essex tells investors in a research note. The analyst says conversations at the RSA Conference were "constructive" regarding FireEye, given him greater confidence that the company is "headed in the right direction for improvement."

He sees a potential upside of 33% in the shares.