William Blair analyst Jason Ader downgraded Cisco Systems (CSCO) to Market Perform from Outperform. The analyst sees "signs of tightening demand" across IT infrastructure, which he believes could pressure growth in Cisco's fiscal 2020, "especially when compared against unusually strong demand in fiscal 2019." Further, one-time tailwinds to the company's fiscal 2019 revenue growth, including ASC 606 and tariff-driven price hikes, will expire, Ader tells investors in a research note. The analyst also sees long-term threats to Cisco from Arista Networks' (ANET) entry into the campus market. Ader now believes upside to Cisco's consensus estimates, as well as multiple expansion, "will be more challenging from here."