Exhibit 99.3

Gigamon Reports Third Quarter 2017 Financial Results

Santa Clara, Calif., October 26, 2017 - Gigamon Inc. (NYSE:GIMO), the leader in traffic visibility solutions, today released financial results for its third quarter ended September 30, 2017.

Third Quarter 2017 Financial Highlights:

Conference Call Information:

In light of the pending acquisition by Elliott Management, Gigamon will not hold its earnings conference call today to discuss its third quarter 2017 results. Additionally, Gigamon will not be providing financial guidance.

Additional Information and Where to Find It

Gigamon will file relevant materials with the Securities and Exchange Commission (the “SEC”) in connection with the proposed merger, including a preliminary proxy statement on Schedule 14A. Under the proposed terms, promptly after filing its definitive proxy statement with the SEC, Gigamon will mail or otherwise make available the definitive

proxy statement and a proxy card to each stockholder entitled to vote at the special meeting relating to the proposed transaction. GIGAMON STOCKHOLDERS AND OTHER INVESTORS ARE ADVISED TO CAREFULLY READ THESE MATERIALS (INCLUDING ANY AMENDMENTS OR SUPPLEMENTS THERETO) AND ANY OTHER RELEVANT DOCUMENTS FILED WITH THE SEC IN RESPECT OF THE PROPOSED MERGER WHEN THEY BECOME AVAILABLE, AS THOSE DOCUMENTS WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED MERGER AND THE PARTIES TO THE PROPOSED MERGER. Gigamon stockholders and other investors may obtain free copies of the definitive proxy statement, the preliminary proxy statement and other relevant materials in connection with the proposed merger (when they become available), along with other documents filed by Gigamon with the SEC, at the SEC’s website (http://www.sec.gov).

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements generally relate to future events, including the timing of the proposed transaction and other information related to the proposed transaction. In some cases, you can identify forward-looking statements because they contain words such as “may,” “will,” “should,” “expects,” “plans,” “anticipates,” “could,” “intends,” “target,” “projects,” “contemplates,” “believes,” “estimates,” “predicts,” “potential” or “continue” or the negative of these words or other similar terms or expressions that concern the proposed transaction and our expectations, strategy, plans or intentions regarding it. Forward-looking statements in this press release include, but are not limited to, our pending acquisition by Elliott Management. Our expectations and beliefs regarding these matters may not materialize, and actual results in future periods are subject to risks and uncertainties that could cause actual results to differ materially from those projected. These risks include the risk that the transaction may not be completed in a timely manner or at all, which may adversely affect our business and the trading price of our common stock; the failure to satisfy the conditions to closing of the transaction, including obtaining regulatory and shareholder approval; the occurrence of any event, change or other circumstance that could give rise to the termination of the definitive agreement; the potential for litigation relating to the transaction; the risk that the definitive agreement may be terminated in circumstances that require us to pay a termination fee; the effect of the announcement or pendency of the transaction on our business

relationships, results of operations and business generally; risks that the proposed transaction disrupts current plans and operations; risk related to diverting management’s attention; and general market, political, economic and business conditions. The forward-looking statements contained in this press release are also subject to other risks and uncertainties, including those more fully described in our filings with the Securities and Exchange Commission, including our Annual Report on Form 10-K for the period ended December 31, 2016 and our most recently filed quarterly report on Form 10-Q. The forward-looking statements in this press release are based on information available to Gigamon as of the date hereof.

Non-GAAP Financial Measures

In addition to disclosing financial measures prepared in accordance with U.S. generally accepted accounting principles (GAAP), this press release and accompanying tables contain certain non-GAAP financial measures that exclude stock-based compensation and related payroll taxes, income tax effects of stock-based compensation expense, non-recurring items such as restructuring charges and advisory services and other costs related to non-routine stockholder matters, and periodic tax items. Non-GAAP financial measures do not have any standardized meaning and our non-GAAP financial measures may not be comparable to similarly titled measures presented by other companies. Gigamon considers these non-GAAP financial measures important because they provide useful measures of the operating performance of the company, exclusive of unusual events or factors that do not directly affect what we consider core to our operating performance, and are used by the company’s management for that purpose. In addition, investors often use similar measures to evaluate the operating performance of a company. We present non-GAAP financial measures for supplemental informational purposes only to provide additional information in understanding the company’s operating results. The non-GAAP financial measures should not be considered a substitute for financial information presented in accordance with GAAP. Please see the reconciliation of non-GAAP financial measures to the most directly comparable GAAP measures attached to this release.

Gigamon

Gigamon (NYSE: GIMO) provides active visibility into physical and virtual network traffic, enabling stronger security and superior performance. Gigamon’s Visibility Fabric and GigaSECURE^®, the industry’s first Security Delivery Platform, deliver advanced intelligence so that security, network and application performance management solutions in enterprise, government and service provider networks operate more efficiently and effectively. See more at www.gigamon.com, the Gigamon Blog, or follow Gigamon on Twitter, LinkedIn or Facebook.

Gigamon Inc.

Consolidated Statements of Operations

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Consolidated Balance Sheets

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Consolidated Statements of Cash Flows

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Reconciliation of GAAP to Non-GAAP Financial Measures

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Reconciliation of GAAP to Non-GAAP Financial Measures (continued)

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