** Shares of networking equipment maker Ciena CIEN.N fall 5.8% to $69 premarket

** Company reports Q4 adjusted EPS of 54 cents vs analysts' estimate of 66 cents, data compiled by LSEG shows

** Gross profit falls 5.4% over the year earlier

** Q4 revenue down 0.5% at $1.12 bln, compared with estimates of $1.10 bln

** Quarterly revenue from its biggest segment, networking platforms, down 2% due to a decline in routing and switching revenue

** Revenue down in regions excluding Americas

** Up to Wednesday's close, stock up 62.7% YTD

(Reporting by Neil J Kanatt in Bengaluru)

((Neil.JKanatt@thomsonreuters.com))