Shares of Infinera Corp. are down 8.2% in premarket trading Thursday after the optical transmission equipment maker reported better-than-expected quarterly results but spoke of pricing pressure from some big competitors. Several analysts maintained their bullish ratings after the numbers came out, however, including William Blair's Dmitry Netis, who rates the stock at outperform. "Infinera demonstrated nice progress in the quarter with the deal pipeline expanding," he wrote, though he also said that the "pricing environment is getting incrementally worse and creating gross margin pressure." He wrote that one of the companies getting more aggressive on price is Ciena Corp. whose shares are down 2.3% in premarket trading. Drexel Hamilton's David Williams reiterated his buy rating and $13 price target on Infinera shares, arguing that "gross and operating leverage remain key drivers to the improved performance with meaningful room for expansion remaining." Shares were up 24% over the past 12 months, as of Wednesday's close, while the S&P 500 has gained 12%.