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): April 5, 2018

MARRONE BIO INNOVATIONS, INC.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (530) 750-2800

(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 Instruction A.2. below):

Indicate by check mark whether the registrant is an emerging growth company as defined in 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).

Emerging growth company [X]

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. [X]

Item 8.01. Other Events.

On April 3, 2018, the Company was named as a defendant in a complaint filed by Piper Jaffray, Inc. (“Piper”) with the Superior Court of the State of Delaware. The Company was informed of and received Piper’s complaint and related documents on April 5, 2018, following the filing of the Company’s Annual Report on Form 10-K for the year ended December 31, 2017. Piper’s complaint alleges one breach of contract claim, specifically, that the Company breached an engagement letter with Piper by failure to pay a $2,000,000 transaction fee, which Piper alleges is due under the engagement letter as a result of the Company’s consummation of its private placement and debt refinancing transactions in February 2018. Piper’s complaint includes a demand for payment the foregoing transaction fee, in addition to interest and costs and expenses incurred in pursuing the action, including reasonable attorneys’ fees. While the Company believes Piper’s complaint is without merit, this matter is at an early stage, and the outcome of this matter is not presently determinable.

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 hereunto duly authorized.