Ciena ( CIEN) was dropping 2.6% to $8.50 in Instinet action before the opening bell Tuesday, a day after the networking company disclosed plans to acquire ONI Systems ( ONIS). ONI was up 7.2%. According to the terms of the merger agreement, Ciena will acquire ONI for $900 million. Ciena will swap 0.7104 share for each share of Ciena. The companies hope to close the merger in the second or third calendar quarter of 2002. Shares of Ciena closed Friday at $8.73, while ONI finished at $5.54. ONI's 52-week high is $45.