The following discussion of our financial condition and results of operations contains forward-looking statements within the meaning of Section 21E of the Securities Exchange Act of 1934 and Section 27A of the Securities Act of 1933. These statements include, but are not limited to, statements about our plans, objectives, expectations, strategies, intentions or other characterizations of future events or circumstances and are generally identified by the words "expects," "anticipates," "intends," "plans," "believes," "seeks," "estimates," and similar expressions. These forward-looking statements are based on current information and expectations and are subject to a number of risks and uncertainties. Our actual results could differ materially from those expressed or implied by these forward-looking statements. Factors that could cause or contribute to such differences include, but are not limited to, those discussed under "Item 1A. Risk Factors" herein and in other documents we file from time to time with the Securities and Exchange Commission. We assume no obligation to revise or update any such forward-looking statements.

Overview

We are a global provider of appliances consisting of software and hardware and services that help companies efficiently and securely manage the delivery, optimization and security of application and data traffic on Internet-based networks, and to optimize the performance and utilization of data storage infrastructure and other network resources. We market and sell our products primarily through multiple indirect sales channels in the Americas (primarily the United States); Europe, the Middle East, and Africa (EMEA); Japan; and the Asia Pacific region (APAC). Enterprise customers (Fortune 1000 or Business Week Global 1000 companies) in the technology, telecommunications, financial services, transportation, education, manufacturing and health care industries, along with government customers, continue to make up the largest percentage of our customer base.

Our management team monitors and analyzes a number of key performance indicators in order to manage our business and evaluate our financial and operating performance on a consolidated basis. Those indicators include:

• Revenues. The majority of our revenues are derived from sales of our Application Delivery Networking (ADN) products including our high end VIPRION chassis and related software modules; BIG-IP Local Traffic Manager, BIG-IP Global Traffic Manager, BIG-IP Link Controller, BIG-IP Application Security Manager, BIG-IP Edge Gateway, BIG-IP WAN Optimization module, BIG-IP Access Policy Manager, WebAccelerator, and FirePass SSL VPN appliance; and our ARX file virtualization products. We also derive revenues from the sales of services including annual maintenance contracts, training and consulting services. We carefully monitor the sales mix of our revenues within each reporting period. We believe customer acceptance rates of our new products and feature enhancements are indicators of future trends. We also consider overall revenue concentration by customer and by geographic region as additional indicators of current and future trends.

• Cost of revenues and gross margins. We strive to control our cost of revenues and thereby maintain our gross margins. Significant items impacting cost of revenues are hardware costs paid to our contract manufacturers, third-party software license fees, amortization of developed technology and personnel and overhead expenses. Our margins have remained relatively stable; however, factors such as sales price, product mix, inventory obsolescence, returns, component price increases and warranty costs could significantly impact our gross margins from quarter to quarter and represent significant indicators we monitor on a regular basis.

• Operating expenses. Operating expenses are substantially driven by personnel and related overhead expenses. Existing headcount and future hiring plans are the predominant factors in analyzing and forecasting future operating expense trends. Other significant operating expenses that we monitor include marketing and promotions, travel, professional fees, computer costs related to the development of new products, facilities and depreciation expenses.

• Liquidity and cash flows. Our financial condition remains strong with significant cash and investments and no long term debt. The increase in cash and investments for the first six months of fiscal year 2012 was primarily due to net income from operations, with operating activities providing cash of $233.5 million. This increase was partially offset by $84.8 million of cash used to repurchase outstanding common stock under our stock repurchase program in the first half of fiscal year 2012. Going forward, we believe the primary driver of cash flows will be net income from operations. On February 22, 2012, we acquired all of the capital stock of Traffix Communication Systems Ltd. (Traffix Systems) for cash of $133.7 million. Capital expenditures for the first six months of fiscal year 2012 were comprised primarily of information technology infrastructure and equipment to support the growth of our core business activities. We will continue to evaluate possible acquisitions of, or investments in businesses, products, or technologies that we believe are strategic, which may require the use of cash.

• Balance sheet. We view cash, short-term and long-term investments, deferred revenue, accounts receivable balances and days sales outstanding as important indicators of our financial health. Deferred revenues increased in the second quarter of fiscal year 2012 due to growth in the amount of annual maintenance contracts purchased on new products and maintenance renewal contracts related to our existing product installation base. Our days sales outstanding for the second quarter of fiscal year 2012 was 49.

Summary of Critical Accounting Policies and Estimates

The preparation of our financial condition and results of operations requires us to make judgments and estimates that may have a significant impact upon our financial results. We believe that, of our significant accounting policies, the following require estimates and assumptions that require complex, subjective judgments by management, which can materially impact reported results: revenue recognition; reserve for doubtful accounts; reserve for product returns; reserve for warranties; accounting for income taxes; stock-based

compensation; investments; goodwill impairment; and the fair value measurements of financial assets and liabilities. None of these accounting policies and estimates, have significantly changed since our annual report on Form 10-K for the year ended September 30, 2011 (Form 10-K). Critical accounting policies and estimates are more fully described in "Management's Discussion and Analysis of Financial Condition and Results of Operations" in the Form 10-K. Actual results may differ from these estimates under different assumptions or conditions.

Results of Operations

The following discussion and analysis should be read in conjunction with our
consolidated financial statements, related notes and risk factors included
elsewhere in this Quarterly Report on Form 10-Q.



                                     Three months ended             Six months ended
                                         March 31,                     March 31,
                                    2012           2011           2012           2011
                                            (in thousands, except percentages)
     Net Revenues
     Products                     $ 205,165      $ 173,710      $ 401,719      $ 345,202
     Services                       134,457        103,862        260,335        201,304

     Total                        $ 339,622      $ 277,572      $ 662,054      $ 546,506

     Percentage of net revenues
     Products                          60.4 %         62.6 %         60.7 %         63.2 %
     Services                          39.6           37.4           39.3           36.8

     Total                            100.0 %        100.0 %        100.0 %        100.0 %

Net revenues. Total net revenues increased 22.4% and 21.1% for the three and six months ended March 31, 2012, respectively, from the same periods in the prior year. Overall revenue growth for the three and six months ended March 31, 2012 was primarily due to increased service and product revenues as a result of our increased installed base of products and increased demand for our core ADN products, including application security and WAN optimization products. International revenues represented 46.6% and 46.8% of total net revenues for the three and six months ended March 31, 2012, respectively, compared to 45.1% and 45.4% for the same periods in the prior year, respectively. We expect international sales will continue to represent a significant portion of net revenues, although we cannot provide assurance that international revenues as a percentage of net revenues will remain at current levels.

Net product revenues increased 18.1% and 16.4% for the three and six months ended March 31, 2012, respectively, from the same periods in the prior year. The increase in net product revenues for the three and six months ended March 31, 2012 was primarily due to an increase of $32.5 million and $59.9 million in sales of our ADN products from the same periods in the prior year, respectively. Sales of our ADN products represented 98.4% and 98.6% of product revenues for the three and six months ended March 31, 2012, respectively, compared to 97.5% and 97.4% of product revenues for the three and six months ended March 31, 2011, respectively.

Net service revenues increased 29.5% and 29.3% for the three and six months ended March 31, 2012, respectively, from the same periods in the prior year. The increase in net service revenues was primarily due to increases in the purchase or renewal of maintenance contracts driven by additions to our installed base of products.

Avnet Technology Solutions and Ingram Micro, two of our worldwide distributors, accounted for 16.6% and 13.9% of our total net revenue for the three months ended March 31, 2012, respectively. Avnet Technology Solutions and Ingram Micro accounted for 17.2% and 13.8% for the six months ended March 31, 2012, respectively. Avnet Technology Solutions accounted for 19.6% and 19.2% of our total net revenue for the three and six months ended March 31, 2011, respectively. Ingram Micro accounted for 18.0% of our accounts receivable as of March 31, 2012. Avnet Technology Solutions accounted for 14.5% of our accounts receivable as of March 31, 2011. No other distributors accounted for more than 10% of total net revenue or receivables.

                                               Three months ended               Six months ended
                                                    March 31,                       March 31,
                                              2012            2011            2012            2011
                                                       (in thousands, except percentages)
Cost of net revenues and Gross Margin
Products                                    $  33,668       $  31,423       $  66,868       $  63,037
Services                                       23,926          19,250          46,332          36,599

Total                                          57,594          50,673         113,200          99,636

Gross profit                                $ 282,028       $ 226,899       $ 548,854       $ 446,870
Percentage of net revenues and Gross
Margin (as a percentage of related net
revenue)
Products                                         16.4 %          18.1 %          16.6 %          18.3 %
Services                                         17.8            18.5            17.8            18.2

Total                                            17.0            18.3            17.1            18.2

Gross profit                                     83.0 %          81.7 %          82.9 %          81.8 %

Cost of net product revenues. Cost of net product revenues consist of finished products purchased from our contract manufacturers, manufacturing overhead, freight, warranty, provisions for excess and obsolete inventory and amortization expenses in connection with developed technology from acquisitions. Cost of net product revenues increased 7.1% and 6.1% for the three and six months ended March 31, 2012, respectively, as compared to the same periods in the prior year. The increase in cost of net product revenues was primarily due to a higher volume of units shipped.

Cost of net service revenues. Cost of net service revenues consist of the salaries and related benefits of our professional services staff, travel, facilities and depreciation expenses. For the three and six months ended March 31, 2012, cost of net service revenues as a percentage of net service revenues remained consistent at 17.8%, compared to 18.5% and 18.2% for the three and six months ended March 31, 2011, respectively. Professional services headcount at the end of March 2012 increased to 583 from 476 at the end of March 2011. In addition, cost of net service revenues included stock-based compensation expense of $2.2 million and $4.4 million for the three and six months ended March 31, 2012, respectively, compared to $1.8 million and $3.6 million for the same periods in the prior year, respectively.

                                               Three months ended               Six months ended
                                                    March 31,                       March 31,
                                              2012            2011            2012            2011
                                                       (in thousands, except percentages)
Operating expenses
Sales and marketing                         $ 110,995       $  89,332       $ 217,233       $ 176,157
Research and development                       43,568          34,507          82,690          67,113
General and administrative                     22,785          19,846          44,462          40,530

Total                                       $ 177,348       $ 143,685       $ 344,385       $ 283,800

Operating expenses (as a percentage of
net revenue)
Sales and marketing                              32.7 %          32.2 %          32.8 %          32.2 %
Research and development                         12.8            12.4            12.5            12.3
General and administrative                        6.7             7.2             6.7             7.4

Total                                            52.2 %          51.8 %          52.0 %          51.9 %

Sales and marketing. Sales and marketing expenses consist of salaries, commissions and related benefits of our sales and marketing staff, the costs of our marketing programs, including public relations, advertising and trade shows, travel, facilities, and depreciation expenses. Sales and marketing expenses increased 24.2% and 23.3% for the three and six months ended March 31, 2012, respectively, from the comparable periods in the prior year. The increase in sales and marketing expense was primarily due to an increase of $16.2 million and $32.1 million in commissions and personnel costs for the three and six months ended March 31, 2012, respectively, from the comparable periods in the prior year. The increased commissions and personnel costs were driven by growth in sales and marketing employee headcount and increased sales volume for the corresponding periods. Sales and marketing headcount at the end of March 2012 increased to 1,198 from 979 at the end of March 2011. Sales and marketing expense included stock-based compensation expense of $9.4 million and $18.4 million for the three and six months ended March 31, 2012, respectively, compared to $8.4 million and $17.1 million for the same periods in the prior year, respectively. The increase in sales and marketing expense was also due to investments in marketing promotions and initiatives aimed at promoting our brand and creating market awareness of our technology and our products.

Research and development. Research and development expenses consist of the salaries and related benefits for our product development personnel, prototype materials and other expenses related to the development of new and improved products, facilities and depreciation expenses. Research and development expenses increased 26.3% and 23.2% for the three and six months ended March 31, 2012, respectively, from the comparable periods in the prior year. The increase in research and development expense was primarily due to an increase of $6.3 million and $11.1 million in personnel costs for the three and six months ended March 31, 2012, respectively, from the comparable periods in the prior year. Research and development headcount at the end of March 2012 increased to 721 from 554 at the end of March 2011. In addition, research and development expense included year over year increases in computer equipment and software costs of $0.7 million and $2.1 million for the three and six months ended March 31, 2012, respectively, to support the development of new and improved products. Research and development expense included stock-based compensation expense of $6.5 million and $12.3 million for the three and six months ended March 31, 2012, respectively, compared to $5.6 million and $11.5 million for the same periods in the prior year, respectively. We expect research and development expenses to remain consistent as a percentage of net revenue in the foreseeable future.

General and administrative. General and administrative expenses consist of the salaries, benefits and related costs of our executive, finance, information technology, human resource and legal personnel, third-party professional service fees, bad debt charges, facilities and depreciation expenses. General and administrative expenses increased 14.8% and 9.7% for the three and six months ended March 31, 2012, respectively, from the comparable periods in the prior year. The increase in general and administrative expense was primarily due to an increase of $1.5 million and $2.8 million in personnel costs for the three and six months ended March 31, 2012, respectively, from the comparable periods in the prior year. In addition, fees paid to outside consultants for legal, audit and tax services increased $1.2 million and $1.9 million for the three and six months ended March 31, 2012, respectively, from the comparable periods in the prior year. Stock-based compensation expense was $4.9 million and $9.6 million for the three and six months ended March 31, 2012, respectively, compared to $5.7 million and $11.7 million for the same periods in the prior year, respectively. General and administrative headcount at the end of March 2012 increased to 303 from 245 at the end of March 2011.

                                               Three months ended              Six months ended
                                                   March 31,                       March 31,
                                              2012            2011           2012            2011
                                                       (in thousands, except percentages)
Other income and income taxes
Income from operations                      $ 104,680       $ 83,214       $ 204,469       $ 163,070
Other income, net                               1,428          1,568           3,289           4,113

Income before income taxes                    106,108         84,782         207,758         167,183
Provision for income taxes                     37,467         29,207          72,625          55,945

Net income                                  $  68,641       $ 55,575       $ 135,133       $ 111,238

Other income and income taxes (as
percentage of net revenue)
Income from operations                           30.8 %         30.0 %          30.9 %          29.8 %
Other income, net                                 0.4            0.5             0.5             0.8

Income before income taxes                       31.2           30.5            31.4            30.6
Provision for income taxes                       11.0           10.5            11.0            10.2

Net income                                       20.2 %         20.0 %          20.4 %          20.4 %

Other income, net. Other income, net, consists primarily of interest income and foreign currency transaction gains and losses. Other income, net, decreased 8.9% and 20.0% for the three and six months ended March 31, 2012, respectively, from the comparable periods in the prior year. The decrease in other income, net for the three and six months ended March 31, 2012 was primarily due to a decrease in interest income compared to the same periods in the prior year. The decrease in interest income for the three and six months ended March 31, 2012 was primarily due to a decline in interest rates from the comparable periods in the prior year.

Provision for income taxes. We recorded a 35.3% provision for income taxes for the three month period ended March 31, 2012. The increase in the effective tax rate compared to the three month period ended March 31, 2011 is primarily due to the expiration of the United States federal credit for Increasing Research Activities on December 31, 2011.

At March 31, 2012, we established a valuation allowance of $0.9 million relative to the deferred tax assets of Traffix Systems, which we acquired in February of 2012. There have been no other valuation allowances established on any of our deferred tax assets in any other jurisdictions in which we operate because we believe that these assets are more likely than not to be realized. In making these determinations we have considered projected future taxable income and ongoing prudent and feasible tax planning strategies in assessing the appropriateness of a valuation allowance. Our net deferred tax assets at March 31, 2012 and March 31, 2011 were $44.5 million and $48.4 million, respectively. Our worldwide effective tax rate may fluctuate based on a number of factors including variations in projected taxable income in the various geographic locations in which we operate, changes in the valuation of our net deferred tax assets, resolution of potential exposures, tax positions taken on tax returns filed in the various geographic locations in which we operate, and the introduction of new accounting standards or changes in tax laws or interpretations thereof in the various geographic locations in which we operate. We have recorded liabilities to address potential tax exposures related to business and income tax positions we have taken that could be challenged by taxing authorities. The ultimate resolution of these potential exposures may be greater or less than the liabilities recorded which could result in an adjustment to our future tax expense.

Liquidity and Capital Resources

Cash and cash equivalents, short-term investments and long-term investments totaled $1,033.5 million as of March 31, 2012 compared to $1,012.8 million as of September 30, 2011, representing an increase of $20.7 million. The increase was primarily due to cash provided by operating activities of $233.5 million for the six months ended March 31, 2012, which was partially offset by $84.8 million of additional cash required for the repurchase of outstanding common stock under our stock repurchase program, and $128.3 million for the acquisition of Traffix Systems. The increase in cash flow from operations for the first six months of fiscal year 2012 resulted from increased net income combined with changes in operating assets and liabilities, as adjusted for various non-cash items

including stock-based compensation, depreciation and amortization charges. Based on our current operating and capital expenditure forecasts, we believe that our existing cash and investment balances, excluding auction rate securities (ARS), together with cash generated from operations should be sufficient to meet our operating requirements for at least the next twelve months.

At March 31, 2012, we held $13.2 million in fair value of tax-exempt ARS, which are variable-rate debt securities and have a long-term maturity with the interest rates being reset through Dutch auctions that are typically held every 7, 28 or 35 days. The securities have historically traded at par and are callable at par at the option of the issuer. Interest is typically paid at the end of each auction period or semi-annually. We limit our investments in ARS to securities that carry a AAA/A- (or equivalent) rating from recognized rating agencies and limit the amount of credit exposure to any one issuer. At the time of initial investment and at the date of this Quarterly Report on Form 10-Q, all of our ARS were in compliance with our investment policy.

Beginning in February 2008, auctions failed for approximately $53.4 million in par value of municipal ARS we held because sell orders exceeded buy orders. When these auctions failed to clear, higher interest rates for those securities went into effect. However, the funds associated with these failed auctions will not be accessible until the issuer calls the security, a successful auction occurs, a buyer is found outside of the auction process or the security matures.

We have no reason to believe that any of the underlying issuers of our ARS are presently at risk of default. The underlying assets of the municipal ARS we hold, including the securities for which auctions have failed, are generally student loans which are guaranteed by the U.S. government. During fiscal years 2011 and 2010, we liquidated $4.0 million and $26.1 million of ARS that we held at par value, respectively. Through March 31, 2012, we have continued to receive interest payments on the ARS in accordance with their terms. We believe we will be able to liquidate our investments without significant loss primarily due to the government guarantee of the underlying securities. However, due to uncertainty in the ARS market, we believe certain of these available-for-sale investments may remain illiquid for longer than twelve months and as a result, we have classified $15.0 million (par value) of our ARS as long-term as of March 31, 2012.

Cash used in investing activities was $171.6 million for the six months ended March 31, 2012, compared to cash used in investing activities of $110.7 million for the same period in the prior year. Investing activities include purchases, sales and maturities of available-for-sale securities, business acquisitions, capital expenditures and changes in restricted cash requirements. The amount of cash used in investing activities for the six months ended March 31, 2012 was primarily due to the purchase of investments partially offset by the sales and maturity of investments and $128.3 million of cash payments, net of cash acquired, to shareholders of Traffix Systems, which was acquired in February 2012.

Cash used in financing activities was $69.2 million for the six months ended March 31, 2012, compared to cash used in financing activities of $46.0 million for the same period in the prior year. Our financing activities for the six months ended March 31, 2012 consisted of cash required for the repurchase of outstanding common stock under our stock repurchase program of $84.8 million, partially offset by cash received from the exercise of employee stock options and stock purchases under our employee stock purchase plan of $10.1 million and . . .