Juniper Networks Inc. shares are off more than 3% in premarket trading Monday after Citi Research analyst Jim Suva downgraded the stock to sell from neutral. "We have picked up recent competitive share gains by Arista and Cisco and this sets up for more share loss to Juniper and too lofty 2H expectations," he wrote. "We do not have any financial cash flow or going concern issues but simply believe the stock price will trade lower as our indications become reality in the months ahead." Suva is also worried about Infinera Corp. due to its share losses and muddied organic growth rates following a recent acquisition. Juniper shares are up 1.7% so far this year, while Infinera shares have dropped 25% and the S&P 500 has gained 19%.