About Proofpoint, Inc.

Proofpoint, Inc. (NASDAQ:PFPT) is a leading next-generation security and compliance company that provides cloud-based solutions for comprehensive threat protection, incident response, secure communications, social media security, compliance, archiving and governance. Organizations around the world depend on Proofpoint’s expertise, patented technologies and on-demand delivery system. Proofpoint protects against phishing, malware and spam, while safeguarding privacy, encrypting sensitive information, and archiving and governing messages and critical enterprise information. More information is available at  www.proofpoint.com.

Proofpoint is a trademark or registered trademark of Proofpoint, Inc. in the U.S. and other countries. All other trademarks contained herein are the property of their respective owners.

Forward-Looking Statements

This press release contains forward-looking statements that involve risks and uncertainties. These forward-looking statements include statements regarding momentum in the company’s business, market position, future growth, benefits of acquisitions, market share and future financial results. It is possible that future circumstances might differ from the assumptions on which such statements are based. Important factors that could cause results to differ materially from the statements herein include: failure to maintain or increase renewals and increased business from existing customers and failure to generate increased business through existing or new channel partner relationships; uncertainties related to continued success in sales growth and market share gains; failure to convert sales opportunities into definitive customer agreements; risks associated with successful implementation of multiple integrated software products and other product functionality; competition, particularly from larger companies with more resources than Proofpoint; risks related to new target markets, new product introductions and innovation and market acceptance thereof; the ability to attract and retain key personnel; changes in strategy; risks associated with management of growth; lengthy sales and implementation cycles, particularly in larger organizations; the time it takes new sales personnel to become fully productive; unforeseen delays in developing new technologies and the uncertain market acceptance of new products or features; technological changes that make Proofpoint's products and services less competitive; security breaches, which could affect our brand; the impact of changes in foreign currency exchange rates; the effect of general economic conditions, including as a result of specific economic risks in different geographies and among different industries; risks related to integrating the employees, customers and technologies of acquired businesses; assumption of unknown liabilities from acquisitions; ability to retain customers of acquired entities; and the other risk factors set forth from time to time in our filings with the SEC, including our Quarterly Report on Form 10-Q for the three months ended March 31, 2015, and the other reports we file with the SEC, copies of which are available free of charge at the SEC's website at  www.sec.gov  or upon request from our investor relations department. All forward- looking statements herein reflect our opinions only as of the date of this release, and Proofpoint undertakes no obligation, and expressly disclaims any obligation, to update forward-looking statements herein in light of new information or future events.

Non-GAAP Financial Measures

We have provided in this release financial information that has not been prepared in accordance with GAAP. We use these non-GAAP financial measures internally in analyzing our financial results and believe they are useful to investors, as a supplement to GAAP measures, in evaluating our ongoing operational performance. We believe that the use of these non-GAAP financial measures provides an additional tool for investors to use in evaluating ongoing operating results and trends and in comparing our financial results with other companies in our industry, many of which present similar non-GAAP financial measures to investors.

Non-GAAP financial measures should not be considered in isolation from, or as a substitute for, financial information prepared in accordance with GAAP. Investors are encouraged to review the reconciliation of these non-GAAP financial measures to their most directly comparable GAAP financial measures below. As previously mentioned, a reconciliation of our non-GAAP financial measures to their most directly comparable GAAP measures has been provided in the financial statement tables included below in this press release.

Non-GAAP gross profit and gross margin. We define non-GAAP gross profit as GAAP gross profit, less stock-based compensation expense and the amortization of intangibles associated with acquisitions. We define non-GAAP gross margin as non-GAAP gross profit divided by GAAP revenue. We consider these non-GAAP financial measures to be useful metrics for management and investors because they exclude the effect of stock-based compensation expense and the amortization of intangibles associated with acquisitions so that our management and investors can compare our recurring core business operating results over multiple periods. There are a number of limitations related to the use of non-GAAP gross profit and non-GAAP gross margin versus gross profit and gross margin, in each case, calculated in accordance with GAAP. For example, stock-based compensation has been and will continue to be for the foreseeable future a significant recurring expense in our business. Stock-based compensation is an important part of our employees' compensation and impacts their performance. In addition, the components of the costs that we exclude in our calculation of non-GAAP gross profit and non-GAAP gross margin may differ from the components that our peer companies exclude when they report their non-GAAP results. Management compensates for these limitations by providing specific information regarding the GAAP amounts excluded from non-GAAP gross profit and non-GAAP gross margin and evaluating non-GAAP gross profit and non-GAAP gross margin together with gross profit and gross margin calculated in accordance with GAAP.

Non-GAAP operating loss. We define non-GAAP operating loss as operating loss less stock-based compensation expense and the amortization of intangibles and costs associated with acquisitions and litigation. We consider this non-GAAP financial measure to be a useful metric for management and investors because they exclude the effect of stock-based compensation expense and the amortization of intangibles and costs associated with acquisitions and litigation so that our management and investors can compare our recurring core business operating results over multiple periods. There are a number of limitations related to the use of non-GAAP operating loss versus operating loss calculated in accordance with GAAP. For example, as noted above, non-GAAP operating loss excludes stock-based compensation expense. In addition, the components of the costs that we exclude in our calculation of non-GAAP operating loss may differ from the components that our peer companies exclude when they report their non-GAAP results of operations. Management compensates for these limitations by providing specific information regarding the GAAP amounts excluded from non-GAAP operating loss and evaluating non- GAAP operating loss together with operating loss calculated in accordance with GAAP.

Non-GAAP net loss. We define non-GAAP net loss as net loss less stock-based compensation expense and the amortization of intangibles and costs associated with acquisitions and litigation, and non-cash interest expense related to the convertible debt discount and non-recurring issuance costs for the convertible debt offering. We consider this non-GAAP financial measure to be a useful metric for management and investors for the same reasons that we use non-GAAP operating loss. However, in order to provide a complete picture of our recurring core business operating results, we also exclude from non-GAAP net loss the tax effects associated with stock-based compensation and the amortization of intangibles and costs associated with acquisitions and litigation, and non-cash interest expense related to the convertible debt discount and non-recurring issuance costs for the convertible debt offering. We used a 4 percent effective tax rate to calculate non-GAAP net loss for the second quarter of

2015 and 9 percent for the second quarter of 2014. We believe that a 6-10% effective tax rate range is a reasonable estimate of the near-term normalized tax rate under our current global operating structure. The same limitations described above regarding our use of non-GAAP operating loss also apply to our use of non-GAAP net loss.

Billings. We define billings as revenue recognized plus the change in deferred revenue from the beginning to the end of the period, but excluding additions to deferred revenue from acquisitions. We consider billings to be a useful metric for management and investors because billings drive deferred revenue, which is an important indicator of the health and visibility of our business, and has historically represented a majority of the quarterly revenue that we recognize. There are a number of limitations related to the use of billings versus revenue calculated in accordance with GAAP. Billings include amounts that have not yet been recognized as revenue, but exclude additions to deferred revenue from acquisitions. We may also calculate billings in a manner that is different from other companies that report similar financial measures. Management compensates for these limitations by providing specific information regarding GAAP revenue and evaluating billings together with revenues calculated in accordance with GAAP.