Equities research analysts at Goldman Sachs Group Inc. downgraded shares of Infinera from a "neutral" rating to a "sell" rating on a valuation call in a research note to investors on Monday according to American Banking News. The analysts set an $8.50 price target on the stock.  Infinera Corporation (Infinera) is a provider of optical networking systems based on Photonic Integration technology. It provides products across the entire range of multi-wavelength optical communications applications, from metro access and metro core through long-haul and submarine transmission.