Optical networking equipment maker Ciena (CIEN

) says it will acquire ONI Systems (ONIS

) in a deal valued at about $900 million. Terms: 0.7104 CIEN share per ONIS share. (2/19)

Sabre Holdings (TSG

) plans to make a $23 per share cash tender offer for all shares of Travelocity.com (TVLY

) that it does not already own. Sabre Holdings currently has about 70% stake. (2/19)

Cytyc Corp. (CYTC

) agrees to acquire Digene Corp. (DIGE

) for $28.81 per share, or about $554 million in cash and stock. (2/19)

Xcel Energy (XEL

) has agreed to buy the rest of NRG Energy (NRG

) that it doesn't own. Xcel Energy currently owns 74% of NRG. Terms: 0.4846 XEL share per NRG share. (2/15)

Some industry pros believe if Viacom's Sumner Redstone doesn't acquire WMS Industries (WMS

) soon, Aristocrat Leisure may beat him to it: BusinessWeek. (2/15)