Bernstein lowered its rating on Corning to market perform from outperform, saying the glass and specialty materials maker is fully valued after a significant increase in its share price.



The company's Gorilla glass product is used in Apple iPhone displays. Corning shares are up 43 percent in the last 12 months through Tuesday.

"Corning has structural advantages from its manufacturing processes, operational efficiencies, economies of scale, and pricing premiums as a result of its technology and quality edge. Corning enjoys consistently higher margins and steady cash flows relative to peers which we believe can be sustained," Bernstein analyst Alberto Moel wrote in a note to clients Wednesday. "However, current multiples and our DCF-based valuation are aligned, with no strong catalysts to either the upside or downside."

Corning last month reported fourth quarter financial results that beat Wall Street estimates on better-than-expected Gorilla Glass 5 sales, according to the analyst. Apple reported much better-than-expected earnings on Tuesday.