UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d)

OF THE SECURITIES EXCHANGE ACT OF 1934

Date of report (Date of earliest event reported): September 20, 2016

NETSCOUT SYSTEMS, INC.

(Exact name of registrant as specified in its charter)

Delaware

(State or other jurisdiction of incorporation)

(978) 614-4000

(Registrant’s telephone number, including area code)

Not Applicable

(Former Name or Former Address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Item 5.03. Amendments to Articles of Incorporation or Bylaws; Change in Fiscal Year.

On September 20, 2016, NetScout Systems, Inc. (the “Company”) held its 2016 annual meeting of stockholders (the “2016 Annual Meeting”). At the 2016 Annual Meeting, the Company’s stockholders approved an amendment to the Company’s Third Amended and Restated Certificate of Incorporation to increase the number of authorized shares of the Company’s common stock from 150,000,000 shares to 300,000,000 shares, as described in the Company’s Definitive Proxy Statement on Schedule 14A filed with the Securities and Exchange Commission on July 28, 2016 (the “2016 Proxy Statement”). The amendment to the Company’s Third Amended and Restated Certificate of Incorporation previously had been approved, subject to stockholder approval, by the Company’s Board of Directors. The amendment to the Company’s Third Amended and Restated Certificate of Incorporation (the “Certificate of Amendment”) was filed with the Secretary of State of the State of Delaware on September 20, 2016.

The above description is qualified in its entirety by reference to the full text of the Certificate of Amendment, which is attached hereto as Exhibit 3.1 and incorporated herein by reference. In addition, a copy of the Company’s Third Amended and Restated Certificate of Incorporation as amended by the Certificate of Amendment is attached hereto as Exhibit 3.2 and incorporated herein by reference.

Item 5.07. Submission of Matters to a Vote of Security Holders.

The 2016 Annual Meeting was held September 20, 2016. As of July 22, 2016, the record date for the 2016 Annual Meeting, 91,991,690 shares of the Company’s common stock were issued and outstanding. A summary of the matters voted upon by stockholders is set forth below.

Item 9.01. Financial Statements and Exhibits.

The Company hereby files the following exhibits:

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Date: September 21, 2016

Exhibit Index