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     Indicate by check mark whether the registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.YESþ NOo

     Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).YESþ NOo

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the definitionsdefinition of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

     Indicate by check mark whether the registrant is a shell company (as determined in Rule 12b-2 of the Exchange Act).YESo NOþ

     Indicate the number of shares outstanding of each of the issuer’s classes of common stock, as of the latest practicable date:

 

     The interim financial statements included herein for Ciena Corporation (“Ciena”) have been prepared by Ciena, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission. In the opinion of management, financial statements included in this report reflect all normal recurring adjustments that Ciena considers necessary for the fair statement of the results of operations for the interim periods covered and of the financial position of Ciena at the date of the interim balance sheets. Certain information and footnote disclosures normally included in the annual financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations. The October 31, 20092010 condensed consolidated balance sheet was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States of America. However, Ciena believes that the disclosures are adequate to understand the information presented. The operating results for interim periods are not necessarily indicative of the operating results for the entire year. These financial statements should be read in conjunction with Ciena’s audited consolidated financial statements and notes thereto included in Ciena’s annual report on Form 10-K for the fiscal year ended October 31, 2009.2010.

     On March 19, 2010, Ciena completed its acquisition of substantially all of the optical networking and Carrier Ethernet assets of Nortel’s Metro Ethernet Networks (“MEN Business”). Ciena’s results of operations for the thirdfirst quarter of fiscal 2010 do not include the results of the MEN Business for the entire period and the results of operations for the nine month period ended July 31, 2010 reflect the operations of the MEN Business beginning on the March 19, 2010 acquisition date.Business. See Note 3 below.

     Ciena has a 52 or 53 week fiscal year, which ends on the Saturday nearest to the last day of October of each year. For purposes of financial statement presentation, each fiscal year is described as having ended on October 31, and each fiscal quarter is described as having ended on January 31, April 30 and July 31 of each fiscal year.

     The preparation of the financial statements and related disclosures in conformity with accounting principles generally accepted in the United States requires management to make estimates and judgments that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Estimates are used for purchase accounting, bad debts, valuation of inventories and investments, recoverability of intangible assets, other long-lived assets and goodwill, income taxes, warranty obligations, restructuring liabilities, derivatives, and contingencies and litigation. Ciena bases its estimates on historical experience and assumptions that it believes are reasonable. Actual results may differ materially from management’s estimates.

     Ciena considers all highly liquid investments purchased with original maturities of three months or less to be cash equivalents. Restricted cash collateralizing letters of creditscredit are included in other current assets and other long-term assets depending upon the duration of the restriction.

     Ciena has certain minority equity investments in privately held technology companies that are classified as other assets. These investments are carried at cost because Ciena owns less than 20% of the voting equity and does not have the ability to exercise significant influence over these companies. These investments involve a high degree of risk as the markets for the technologies or products manufactured by these companies are usually early stage at the time of Ciena’s investment and such markets may never be significant. Ciena could lose its entire investment in some or all of these companies. Ciena monitors these investments for impairment and makes appropriate reductions in carrying values when necessary.

     Inventories are stated at the lower of cost or market, with cost computed using standard cost, which approximates actual cost, on a first-in, first-out basis. Ciena records a provision for excess and obsolete inventory when an impairment has been identified.

     Effective upon the March 19, 2010 completion of the acquisition of the MEN Business, Ciena reorganized its internal organizational structure and the management of its business. Ciena’s chief operating decision maker, its chief executive officer, evaluates performance and allocates resources based on multiple factors, including segment profit (loss) information for the following product categories: (i) Packet-Optical Transport; (ii) Packet-Optical Switching; (iii) Carrier Ethernet Service Delivery; and (iv) Software and Services. Operating segments are defined as components of an enterprise: that engage in business activities which may earn revenue and incur expense; for which discrete financial information is available; and for which such information is evaluated regularly by the chief operating decision maker for purposes of allocating resources and assessing performance. Ciena considers the four product categories above to be its operating segments for reporting purposes. See Notes 3 and 20.

     Ciena’s long-livedLong-lived assets include: equipment, furniture and fixtures; intangible assets; and maintenance spares. Ciena tests long-lived assets for impairment whenever triggering events or changes in circumstances indicate that the assets’ carrying amount is not recoverable from its undiscounted cash flows. An impairment loss is measured as the amount by which the carrying amount of the asset or asset group exceeds its fair value. Ciena’s long-lived assets are assigned to reporting unitsasset groups which represent the lowest level for which cash flows can be identified.

     Equipment, Furniture and Fixtures

     Equipment, furniture and fixtures are recorded at cost. Depreciation and amortization are computed using the straight-line method over useful lives of two years to five years for equipment, furniture and fixtures and the shorter of useful life or lease term for leasehold improvements.

     Qualifying internal use software and website development costs incurred during the application development stage that consist primarily of outside services and purchased software license costs, are capitalized and amortized straight-line over the estimated useful life.lives of two years to five years.

     Intangible Assets

     Ciena has recorded finite-lived and indefinite lived intangible assets as a result of several acquisitions. Finite-lived intangible assets are carried at cost less accumulated amortization. Amortization is computed using the straight-line method over the expected economic lives of the respective assets, from nine months to seven years, which approximates the use of intangible assets.

     Substantially all of Ciena’s cash and cash equivalents and short-term and long-term investments in marketable debt securities are maintained at two major U.S. financial institutions. The majority of Ciena’s cash equivalents consist of money market funds. Deposits held with banks may exceed the amount of insurance provided on such deposits. Generally, these deposits may be redeemed upon demand and, therefore, management believes that they bear minimal risk.

     Historically, a large percentage of Ciena’s revenue has been the result of sales to a small number of communications service providers. Consolidation among Ciena’s customers has increased this concentration. Consequently, Ciena’s accounts receivable are concentrated among these customers. See Notes 98 and 2019 below.

     Additionally, Ciena’s access to certain materials or components is dependent upon sole or limited source suppliers. The inability of any supplier to fulfill Ciena’s supply requirements could affect future results. Ciena relies on a small number of contract manufacturers to perform the majority of the manufacturing for its products. If Ciena cannot effectively manage these manufacturers and forecast future demand, or if they fail to deliver products or components on time, Ciena’s business and results of operations may suffer.

     Ciena recognizes revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the price to the buyer is fixed or determinable; and collectibility is reasonably assured. Customer purchase agreements and customer purchase orders are generally used to determine the existence of an arrangement. Shipping documents and evidence of customer acceptance, when applicable, are used to verify delivery.delivery or services rendered. Ciena assesses whether the price is fixed or determinable based on the payment terms associated with the transaction and whether the sales price is subject to refund or adjustment. Ciena assesses collectibility based primarily on the creditworthiness of the customer as determined by credit checks and analysis, as well as the customer’s payment history. Revenue for maintenance services is generally deferred and recognized ratably over the period during which the services are to be performed.

     Ciena applies the percentage of completion method to long-term arrangements where it is required to undertake significant production, customizations or modification engineering, and reasonable and reliable estimates of revenue and cost are available. Utilizing the percentage of completion method, Ciena recognizes revenue based on the ratio of actual costs incurred to date to total estimated costs expected to be incurred. In instances that do not meet the percentage of completion method criteria, recognition of revenue is deferred until there are no uncertainties regarding customer acceptance.

     Some of Ciena’s communications networking equipment is integrated with software that is essential to the functionality of the equipment. Software revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred, the fee is fixed or determinable, and collectibility is probable. In instances where final acceptance criteria of the productsoftware is specified by the customer, revenue is deferred until there are no uncertainties regarding customer acceptance.

     Arrangements with customers may include multiple deliverables, including any combination of equipment, services and software. If multiple element arrangements include software or software-related elements that are essential to the equipment, Ciena allocates the arrangement fee to be allocated to thoseamong separate units of accounting. Multiple element arrangements that include software are separated into more than one unit of accounting if the functionality of the delivered element(s) is not dependent on the undelivered element(s), there is vendor-specific objective evidence (“VSOE”) of the fair value of the undelivered element(s), and general revenue recognition criteria related to the delivered element(s) have been met. The amount of product and services revenue recognized is affected by Ciena’s judgments as to whether an arrangement includes multiple elements and, if so, whether vendor-specific objective evidenceVSOE of fair value exists. VSOE is established based on Ciena’s standard pricing and discounting practices for the specific product or service when sold separately. In determining VSOE, Ciena requires that a substantial majority of the selling prices for a product or service fall within a reasonably narrow pricing range. Changes to the elements in an arrangement and Ciena’s ability to establish vendor-specific objective evidenceVSOE for those elements could affect the timing of revenue

     Ciena provides for the estimated costs to fulfill customer warranty obligations upon the recognition of the related revenue. Estimated warranty costs include estimates for material costs, technical support labor costs and associated overhead. The warranty liability is included in cost of goods sold and determined based upon actual warranty cost experience, estimates of component failure rates and management’s industry experience. Ciena’s sales contracts do not permit the right of return of product by the customer after the product has been accepted.

     Ciena’s allowance for doubtful accounts is based on its assessment, on a specific identification basis, of the collectibility of customer accounts. Ciena performs ongoing credit evaluations of its customers and generally has not required collateral or other forms of security from its customers. In determining the appropriate balance for Ciena’s allowance for doubtful accounts, management considers each individual customer account receivable in order to determine collectibility. In doing so, management considers creditworthiness, payment history, account activity and communication with such customer. If a customer’s financial condition changes, Ciena may be required to record an allowance for doubtful accounts, which would negatively affect its results of operations.

     Ciena charges all research and development costs to expense as incurred. Types of expense incurred in research and development include employee compensation, prototype, consulting, depreciation, facility costs and information technologies.

     Ciena expenses all advertising costs as incurred.

     Ciena expenses legal costs associated with litigation defense as incurred.

     Ciena measures and recognizes compensation expense for share-based awards based on estimated fair values on the date of grant. Ciena estimates the fair value of each option-based award on the date of grant using the Black-Scholes option-pricing model. This model is affected by Ciena’s stock price as well as estimates regarding a number of variables including expected stock price volatility over the expected term of the award and projected employee stock option exercise behaviors. Ciena estimates the fair value of each share-based award based on the fair value of the underlying common stock on the date of grant. In each case, Ciena only recognizes expense to its consolidated statement of operations for those options or shares that are expected ultimately to vest. Ciena uses two attribution methods to record expense, the straight-line method for grants with service-based vesting and the graded-vesting method, which considers each performance period or tranche separately, for all other awards. See Note 1817 below.

     Ciena recognizes windfall tax benefits associated with the exercise of stock options or release of restricted stock units directly to stockholders’ equity only when realized. A windfall tax benefit occurs when the actual tax benefit realized by Ciena upon an employee’s disposition of a share-based award exceeds the deferred tax asset, if any, associated with the award that Ciena had recorded. When assessing whether a tax benefit relating to share-based compensation has been realized, Ciena follows the tax law “with-and-without” method. Under the with-and-without method, the windfall is considered realized and recognized for financial statement purposes only when an incremental benefit is provided after considering all other tax benefits including Ciena’s net operating losses. The with-and-without method results in the windfall from share-based compensation awards always being effectively the last tax benefit to be considered. Consequently, the windfall attributable to share-based compensation will not be considered realized in instances where Ciena’s net operating loss carryover (that is unrelated to windfalls) is sufficient to offset the current year’s taxable income before considering the effects of current-year windfalls.

     Ciena is subject to the possibility of various losses arising in the ordinary course of business. These may relate to disputes, litigation and other legal actions. Ciena considers the likelihood of loss or the incurrence of a liability, as well as Ciena’s ability to reasonably estimate the amount of loss, in determining loss contingencies. An estimated loss contingency is accrued when it is probable that a liability has been incurred and the amount of loss can be reasonably estimated. Ciena regularly evaluates current information available to it to determine whether any accruals should be adjusted and whether new accruals are required.

     The carrying value of Ciena’s cash and cash equivalents, accounts receivable, accounts payable, and accrued liabilities, approximates fair market value due to the relatively short period of time to maturity. The fair value of investments in marketable debt securities is determined using quoted market prices for those securities or similar financial instruments. For information related to the fair value of Ciena’s convertible notes, see Note 815 below.

     Fair value for the measurement of financial assets and liabilities is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. Ciena utilizes a valuation hierarchy for disclosure of the inputs for fair value measurement. This hierarchy prioritizes the inputs into three broad levels as follows:

     Ciena’s 4.0% convertible senior notes include a redemption feature that is accounted for as a separate embedded derivative. The embedded redemption feature is recorded at fair value on a recurring basis and these changes are included in interest and other income, (expense), net on the Condensed Consolidated Statement of Operations.

     Ciena calculates basic earnings per share (EPS) by dividing earnings attributable to common stock by the weighted-average number of common shares outstanding for the period. Diluted EPS includes other potential dilutive common stock that would occur if securities or other contracts to issue common stock were exercised or converted into common stock. Ciena uses a dual presentation of basic and diluted EPS on the face of its income statement. A reconciliation of the numerator and denominator used for the basic and diluted EPS computations is set forth in Note 17.16.

     In accordance with the agreements for the acquisition, the initial $773.8 million aggregate purchase price which was payable in cash and convertible notes, was subsequently adjusted downward by $80.6 million based upon the amount of net working capital transferred to Ciena at closing. Prior to closing, Ciena elected to replace the $239.0 million in aggregate principal of convertible notes that were to be issued to Nortel as part of the aggregate purchase price with cash equivalent to 102% of the face amount of the notes replaced, or $243.8 million. Ciena completed a private placement of 4.0% Convertible Senior Notes due March 15, 2015 in aggregate principal amount of $375.0 million which funded this election and reduced the amount of cash on hand required to fund the aggregate purchase price. See Note 16 below. As a result, Ciena paid $693.2 million in cash for the aggregatepurchase of the MEN Business.

     In connection with the acquisition, Ciena entered into an agreement with Nortel to lease the “Lab 10” building on Nortel’s Carling Campus in Ottawa, Canada (the “Carling lease”) for a term of ten years. The lease agreement contained a provision that allowed Nortel to reduce the term of the lease, and in exchange, Ciena could receive a payment of up to $33.5 million. This amount was placed into escrow by Nortel in accordance with the acquisition agreements. The fair value of this contingent refund right of $16.4 million was recorded as a reduction to the consideration paid, resulting in a purchase price was $693.2of $676.8 million.

     On October 19, 2010, Nortel issued a public announcement that it had entered into a sale agreement of its Carling campus with Public Works and Government Services Canada (PWGSC) and had been directed to exercise its early termination rights under the Carling lease, shortening the lease term from ten years to five years. As a result, and based on this change in circumstances and expected outcome probability, during the fourth quarter of fiscal 2010 Ciena recorded an unrealized gain of $13.8 million consisting entirelyresulting in a fair value of cash.$30.2 million for the contingent consideration right. During the first quarter of fiscal 2011, Ciena received notice of early termination from Nortel and the corresponding payment of $33.5 million described above, resulting in a gain of $3.3 million.

     Given the structure of the transaction as an asset carve-out from Nortel, Ciena expects that thethis transaction will resulthas resulted in a costly and complex integration with a number of operational risks. Ciena expects to incur approximately $180 million in costs associated with equipment and information technology, transaction expense, severance expense and consulting and third party service fees associated with the integration, with the majority of these costs to be incurred inintegration. During fiscal 2010. In addition to these costs, Ciena has incurred inventory obsolescence charges and may incur additional expenses related to, among other things, facilities restructuring. As a result, the expense that Ciena incurs and recognizes for financial statement purposes will be significantly higher than the estimated costs above. As of July 31, 2010, Ciena has incurred $83.3$101.4 million in transaction, consulting and third party service fees, $4.0$8.5 million in severancerestructuring expense, and an additional $10.8$12.4 million in costs primarily related to purchases of capitalized information technology equipment. During the first quarter of fiscal 2011, Ciena incurred $24.2 million in transaction, consulting and third party service fees, $1.5 million in restructuring expense, and an additional $4.1 million primarily related to purchases of capitalized information technology equipment. In addition to the estimated costs above, Ciena also expects to incur significant transition services expense. Ciena is currently relying upon an affiliate of Nortel to perform certain critical operational and business support functions during an interim integration period. Ciena can utilize certain of these support services for a period of up to 24 months following the acquisition of the MEN Business, 12 months in Europe, Middle East and Africa, (EMEA). The cost of these transition services is estimated to be approximately $94 million annually. The actual expense will depend upon the scope of the services that Ciena utilizes and the time within which Ciena is able to complete the planned transfer of these services to internal resources or other third party providers.

     Unbilled receivables represent unbilled claims for which Ciena will invoice customers upon its completion of the acquired projects.

     Under the acquisition method of accounting, Ciena revalued the acquired finished goods inventory to fair value, which was determined to be most appropriately recognized as the estimated selling price less the sum of (a) costs of disposal, and (b) a reasonable profit allowance for Ciena’s selling effort. This revaluation resulted in an increase in inventory carrying value of approximately $39.7 million for marketable inventory offset by a decrease of $2.5 million for unmarketable inventory.

     Prepaid expenses and other include product demonstration units used to support research and development projects and indemnification assets related to uncertain tax contingencies acquired and recorded as part of other long-term obligations. Other long-term assets represent spares used to support customer maintenance commitments.

     Developed technology represents purchased technology which hasthat had reached technological feasibility and for which development had been completed as of the date of the acquisition. Developed technology will be amortized on a straight line basis over its estimated useful lives of two to seven years.

     In-process research and development represents development projects that had not reached technological feasibility at the time of the acquisition. In-processThis in-process research and development assets will be impaired, if abandoned, orwas completed during the fourth quarter of fiscal 2010 and is being amortized in future periods, depending uponover the abilityperiod of Ciena to use the research and development in future periods. Future expendituresseven years. Expenditures to complete the in-process research and development projects will bewere expensed as incurred.

     To consolidate Ciena’s global distribution centers and related operations, on February 28, 2011, Ciena proposed changes in its distribution model that may affect 50 to 60 roles related to its supply chain operations and workforce in Monkstown, Northern Ireland. Execution of any specific reorganization or headcount reduction is subject to local legal requirements, including notification and consultation processes with employees and employee representatives. If these proposals move forward, Ciena expects this action to result in a restructuring charge in the activity and balancerange of $2.0 million to $3.0 million in the restructuring liability accounts for the nine months ended July 31, 2009 (in thousands):

     As of the dates indicated, short-termOctober 31, 2010 and long-termJanuary 31, 2011, Ciena did not have any investments are comprised of the following (in thousands):

     As of the date indicated, the following table summarizes the fair value of assets that are recorded at fair value on a recurring basis (in thousands):

     As of the dates indicated, inventories are comprised of the following (in thousands):

     As of the dates indicated, equipment, furniture and fixtures are comprised of the following (in thousands):

     As of the dates indicated, accrued liabilities are comprised of the following (in thousands):