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): December 15, 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.  ☐

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

On December 15, 2017, the board of directors (the “Board”) of Imperva, Inc. (“Imperva”) approved amendments to the Amended and Restated Bylaws (the “Bylaws”) of Imperva to permit a stockholder or a group of up to 20 stockholders that has maintained continuous ownership of at least 3% of Imperva’s common stock for at least three years to include nominees in Imperva’s proxy materials for an annual meeting of stockholders, provided the stockholder(s) and nominee(s) satisfy the requirements specified in the Bylaws. The number of director nominees that may be so included is limited to the greater of two or 20% of the total number of directors. The amended Bylaws became effective as of December 15, 2017.

The foregoing summary is qualified in its entirety by reference to the full text of the Bylaws, a copy of which is filed as Exhibit 3.1 to this report and is incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

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.