UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 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): October 17, 2017

Imperva, Inc.

(Exact name of Registrant as Specified in Its Charter)

Registrant’s Telephone Number, Including Area Code: (650) 345-9000

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 (see General Instructions A.2. below):

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

On October 19, 2017, Imperva, Inc. (“Imperva”) issued a press release announcing certain preliminary financial results for the quarter ended September 30, 2017. A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K (this “Current Report”).

The information in Item 2.02 of this Current Report, including Exhibit 99.1, is being furnished and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section or Sections 11 and 12(a)(2) of the Securities Act of 1933, as amended. The information in this Item 2.02 shall not be incorporated by reference in any registration statement or other document filed by Imperva with the Securities and Exchange Commission, whether made before or after the date of this Current Report, regardless of any general incorporation language in such filing, except as shall be expressly set forth by specific reference in such a filing.

Departure of Director

On October 17, 2017, Charles Giancarlo informed Imperva of his intention to resign from the Board of Directors (including the Compensation Committee, Nominating and Corporate Governance Committee and Acquisitions Committee), effective immediately.

Mr. Giancarlo’s resignation is not the result of any disagreement with Imperva or the Board of Directors on any matter. Imperva has provided Mr. Giancarlo a copy of this disclosure prior to filing this Current Report and has informed him that he may provide Imperva with a letter stating whether he agrees or disagrees with the statements made in this Current Report. Any letter received by Imperva from Mr. Giancarlo will be filed as an exhibit to this Current Report by way of amendment within three business days of receipt.

(d) Exhibits.

2

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.