UPDATE: Gabelli Downgrades Stratasys On Valuation Concern

Stratasys (NASDAQ: SSYS) shares are up nearly 16 percent since the company beat second-quarter expectations by a wide margin Thursday. But a research firm downgraded the shares Friday citing valuation.

The 3D printer maker posted adjusted earnings of $0.55 per share while revenue grew 68 percent to $178.5 million. Analysts expected $0.45 on revenue of $156.6 million.

Gabelli's Hendi Susanto said although she favors Stratasys' potential for margin expansion and growth opportunity in 3D printing, "at the current share price we're changing our recommendation to Hold from Buy."

Yet even with the recent run up, Stratasys shares are down more than 15 percent year to date.

Stratasys said recently it will begin selling its printers at Home Depot stores later this year. Last week Stratasys said it will sponsor a NASCAR vehicle.

Stratasys traded recently at $13.68, nearly unchanged.