Ciena expects $5.0 to $6.0 million Q3 GAAP loss related to commercial paper investments

Linthicum, MD — 07/18/2008

Ciena® Corporation (NASDAQ: CIEN) today announced that it expects to recognize a GAAP loss totaling between $5.0 million and $6.0 million in the third quarter of fiscal 2008, relating to commercial paper investments in Rhinebridge LLC and SIV Portfolio plc (formerly known as Cheyne Finance plc). Ciena had previously recognized a loss of $13.0 million related to its investment in these two structured investment vehicles (SIVs), each of which entered into receivership and failed to make payment at maturity during the fourth quarter of Ciena’s fiscal 2007.

At April 30, 2008, Ciena’s commercial paper issued by these SIVs had a carrying value of $25.6 million. The estimated GAAP loss for the third quarter is based upon valuation information provided by Ciena’s investment manager on July 16, 2008 in connection with the restructuring of these SIVs. This estimated GAAP loss will not affect Ciena’s income from operations for the third quarter of fiscal 2008. As stated previously, Ciena believes that its SIV-related exposure is limited to these two investments.

About Ciena

Ciena specializes in network transition. We provide the flexible platforms, intelligent software and professional services to build converged networks for enhanced services and applications. With a growing global presence, Ciena leverages its heritage of practical innovation to deliver maximum performance and economic value in communications networks worldwide. For more information, visit www.ciena.com [1].