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; FirePass SSL VPN appliance; Traffix diameter signaling products; and 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 three months of fiscal year 2013 was primarily due to net income from operations, with operating activities providing cash of $144.8 million. This increase was partially offset by $50.0 million of cash used to repurchase outstanding common stock under our stock repurchase program in the first three months of fiscal year 2013. Going forward, we believe the primary driver of cash flows will be net income from operations. Capital expenditures for the first three months of fiscal year 2013 were comprised primarily of information technology infrastructure and equipment purchases to support the growth of our core business activities, and expenses related to the addition and expansion of our worldwide facilities. 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 first quarter of fiscal year 2013 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 first quarter of fiscal year 2013 was 51.

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, 2012 (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
                                                  December 31,
                                          2012                     2011
                                       (in thousands, except percentages)
       Net Revenues
       Products                     $        204,712         $        196,554
       Services                              160,739                  125,878

       Total                        $        365,451         $        322,432

       Percentage of net revenues
       Products                                 56.0 %                   61.0 %
       Services                                 44.0                     39.0

       Total                                   100.0 %                  100.0 %

Net revenues. Total net revenues increased 13.3% for the three months ended December 31, 2012, from the same period in the prior year. Overall revenue growth for the three months ended December 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 our application security products. International revenues represented 46.7% of total net revenues for the three months ended December 31, 2012, compared to 47.0% for the same period in the prior year. 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 4.2% for the three months ended December 31, 2012, from the same period in the prior year. The increase in net product revenues for the three months ended December 31, 2012 was primarily due to an increase of $8.2 million in sales of our ADN products from the same period in the prior year. Sales of our ADN products represented 98.8% of product revenues for the three months ended December 31, 2012, compared to 98.7% of product revenues for the three months ended December 31, 2011.

Net service revenues increased 27.7% for the three months ended December 31, 2012, from the same period 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, Ingram Micro, and Westcon, three of our worldwide distributors, accounted for 16.9%, 15.2%, and 11.0% of our total net revenue for the three months ended December 31, 2012, respectively. Avnet Technology Solutions and Ingram Micro accounted for 17.9% and 13.7% of our total net revenue for the three months ended December 31, 2011, respectively. Avnet Technology Solutions and Ingram Micro accounted for 11.2% and 10.3% of our accounts receivable as of December 31, 2012, respectively. Avnet Technology Solutions accounted for 15.6% of our accounts receivable as of December 31, 2011. No other distributors accounted for more than 10% of total net revenue or receivables.

                                                                Three months ended
                                                                   December 31,
                                                           2012                     2011
                                                        (in thousands, except percentages)
Cost of net revenues and Gross Margin
Products                                             $         31,792         $         33,200
Services                                                       29,093                   22,406

Total                                                          60,885                   55,606

Gross profit                                         $        304,566         $        266,826
Percentage of net revenues and Gross Margin (as a
percentage of related net revenue)
Products                                                         15.5 %                   16.9 %
Services                                                         18.1                     17.8

Total                                                            16.7                     17.2

Gross profit                                                     83.3 %                   82.8 %

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 decreased 4.2% for the three months ended December 31, 2012, as compared to the same period in the prior year.

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 months ended December 31, 2012, cost of net service revenues as a percentage of net service revenues were 18.1%, compared to 17.8% for the three months ended December 31, 2011. Professional services headcount at the end of December 2012 increased to 701 from 538 at the end of December 2011. In addition, cost of net service revenues included stock-based compensation expense of $2.6 million for the three months ended December 31, 2012, compared to $2.2 million for the same period in the prior year.

                                                                    Three months ended
                                                                       December 31,
                                                              2012                      2011
                                                            (in thousands, except percentages)
Operating expenses
Sales and marketing                                     $        122,268          $        106,238
Research and development                                          48,541                    39,122
General and administrative                                        24,673                    21,677

Total                                                   $        195,482          $        167,037

Operating expenses (as a percentage of net revenue)
Sales and marketing                                                 33.5 %                    33.0 %
Research and development                                            13.3                      12.1
General and administrative                                           6.7                       6.7

Total                                                               53.5 %                    51.8 %

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 15.1% for the three months ended December 31, 2012, from the comparable period in the prior year. The increase in sales and marketing expense was primarily due to an increase of $11.7 million in

commissions and personnel costs. The increased commissions and personnel costs were driven primarily by growth in sales and marketing employee headcount and increased sales volume for the corresponding periods. Sales and marketing headcount at the end of December 2012 increased to 1,296 from 1,141 at the end of December 2011. Sales and marketing expense included stock-based compensation expense of $10.6 million for the three months ended December 31, 2012, compared to $9.1 million for the same period in the prior year. 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 of 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 24.1% for the three months ended December 31, 2012, from the comparable period in the prior year. The increase in research and development expense was primarily due to an increase of $7.4 million in personnel costs for the three months ended December 31, 2012, from the comparable period in the prior year. Research and development headcount at the end of December 2012 increased to 802 from 646 at the end of December 2011. Research and development expense included stock-based compensation expense of $7.8 million for the three months ended December 31, 2012, compared to $5.8 million for the same period in the prior year. 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 13.8% for the three months ended December 31, 2012, from the comparable period in the prior year. The increase in general and administrative expense was primarily due to an increase of $1.5 million in personnel costs for the three months ended December 31, 2012, from the comparable period in the prior year. Stock-based compensation expense was $5.4 million for the three months ended December 31, 2012, compared to $4.7 million for the same period in the prior year. General and administrative headcount at the end of December 2012 increased to 328 from 291 at the end of December 2011.

                                                                Three months ended
                                                                   December 31,
                                                          2012                      2011
                                                        (in thousands, except percentages)
Other income and income taxes
Income from operations                              $        109,084          $         99,789
Other income, net                                              1,550                     1,861

Income before income taxes                                   110,634                   101,650
Provision for income taxes                                    41,141                    35,158

Net income                                          $         69,493          $         66,492

Other income and income taxes (as percentage of
net revenue)
Income from operations                                          29.9 %                    30.9 %
Other income, net                                                0.4                       0.6

Income before income taxes                                      30.3                      31.5
Provision for income taxes                                      11.3                      10.9

Net income                                                      19.0 %                    20.6 %

Other income, net. Other income, net, consists primarily of interest income and foreign currency transaction gains and losses. Other income, net, for the three months ended December 31, 2012, remained relatively consistent compared to the same period in the prior year.

Provision for income taxes. We recorded a 37.2% provision for income taxes for the three month period ended December 31, 2012. The increase in the effective tax rate compared to the three month period ended December 31, 2011 is primarily due to the expiration of the United States federal credit for Increasing Research Activities on December 31, 2011 and an increase in non-deductible stock-based compensation attributable to foreign based employees. On January 2, 2013, the President signed into law the American Taxpayer Relief Act of 2012. As part of that legislation, the United States federal credit for increasing research activities (the "Credit") was extended retroactive to January 1, 2012 through December 31, 2013. For financial reporting purposes, we will take into account the tax effects of this legislation, as it relates to the Credit, in the second quarter of our fiscal year 2013.

At December 31, 2012, there have been no material valuation allowances established on any of our deferred tax assets in any of the 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 December 31, 2012 and December 31, 2011 were $46.6 million and $43.8 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 $1,289.0 million as of December 31, 2012 compared to $1,195.0 million as of September 30, 2012, representing an increase of $94.0 million. The increase was primarily due to cash provided by operating activities of $144.8 million for the three months ended December 31, 2012, which was partially offset by $50.0 million of additional cash required for the repurchase of outstanding common stock under our stock repurchase program. The increase in cash flow from operations for the first three months of fiscal year 2013 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.

Cash used in investing activities was $133.4 million for the three months ended December 31, 2012, compared to cash used in investing activities of $67.4 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 three months ended December 31, 2012 was primarily due to the purchase of investments and capital expenditures related to maintaining our operations worldwide partially offset by the sales and maturity of investments.

Cash used in financing activities was $37.9 million for the three months ended December 31, 2012, compared to cash used in financing activities of $23.5 million for the same period in the prior year. Our financing activities for the three months ended December 31, 2012 consisted primarily of cash required for the repurchase of outstanding common stock under our stock repurchase program of $50.0 million, partially offset by cash received from the exercise of employee stock options and stock purchases under our employee stock purchase plan of $11.6 million.

Obligations and Commitments

As of December 31, 2012, our principal commitments consisted of obligations outstanding under operating leases. We lease our facilities under operating leases that expire at various dates through 2023. There have been no material changes in our principal lease commitments compared to those discussed in the Form 10-K.

We outsource the manufacturing of our pre-configured hardware platforms to contract manufacturers who assemble each product to our specifications. Our agreement with our largest contract manufacturer allows them to procure component inventory on our behalf based upon a rolling production forecast. We are contractually obligated to purchase the component inventory in accordance with the forecast, unless we give notice of order cancellation in advance of applicable lead times. As of December 31, 2012, we were committed to purchase approximately $16.6 million of such inventory during the next 30 day period.

Recent Accounting Pronouncements

The anticipated impact of recent accounting pronouncements is discussed in Note 1 to the accompanying Notes to Consolidated Financial Statements of this Quarterly Report on Form 10-Q.

Risk Factors that May Affect Future Results

This Quarterly Report on Form 10-Q contains forward-looking statements that involve risks and uncertainties. Our business, operating results, financial performance and share price may be materially adversely affected by a number of factors, including but not limited to the following risk factors, any one of which could cause actual results to vary materially from anticipated results or from those expressed in any forward-looking statements made by us in this Quarterly Report on Form 10-Q or in other reports, press releases or other statements issued from time to time. Additional factors that may cause such a difference are set forth elsewhere in this Quarterly Report on Form 10-Q.

Our quarterly and annual operating results may fluctuate in future periods, which may cause our stock price to fluctuate

Our quarterly and annual operating results have varied significantly in the past and could vary significantly in the future, which makes it difficult for us to predict our future operating results. Our operating results may fluctuate due to a variety of factors, many of which are outside of our control, including the changing and recently volatile U.S. and global economic environment, which may cause our stock price to fluctuate. In particular, we anticipate that the size of customer orders may increase as we continue to focus on larger business accounts. A delay in the recognition of revenue, even from just one account, may have a significant negative impact on our results of operations for a given period. In the past, a majority of our sales have been realized near the end of a quarter. Accordingly, a delay in an anticipated sale past the end of a particular quarter may negatively impact our results of operations for that quarter, or in some cases, that fiscal year. Additionally, we have exposure to the credit risks of some of our customers and sub-tenants. Although we have programs in place that are designed to monitor and mitigate the associated risk, there can be no assurance that such programs will be effective in reducing our credit risks adequately. We monitor individual payment capability in granting credit arrangements, seek to limit the total credit to amounts we believe our customers can pay and maintain reserves we believe are adequate to cover exposure for potential losses. If there is a deterioration of a sub-tenant's or a major customer's creditworthiness or actual defaults are higher than expected, future losses, if incurred, could harm our business and have a material adverse effect on our operating results. Further, our operating results may be below the expectations of securities analysts and investors in future quarters or years. Our failure to meet these expectations will likely harm the market price of our common stock. Such a decline could occur, and has occurred in the past, even . . .