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): January 15, 2020

CLEARSIGN TECHNOLOGIES CORPORATION

(Exact name of registrant as specified in Charter)

12870 Interurban Avenue South

Seattle, Washington 98168

(Address of Principal Executive Offices)

206-673-4848

(Issuer Telephone number)

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 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

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. ¨

Securities registered pursuant to Section 12(b) of the Act:

On January 15, 2020, ClearSign Technologies Corporation (the “Company”) received a letter (the “Notice”) from the Listing Qualifications Staff (the “Staff”) of The Nasdaq Stock Market LLC (“Nasdaq”) indicating that, based upon the closing bid price of the Company’s common stock for the last 30 consecutive business days beginning on November 29, 2019 and ending on January 13, 2020, the Company no longer meets the requirement to maintain a minimum bid price of $1 per share, as set forth in Nasdaq Listing Rule 5550(a)(2).

In accordance with Nasdaq Listing Rule 5810(c)(3)(A), the Company has been provided a period of 180 calendar days, or until July 13, 2020, in which to regain compliance. In order to regain compliance with the minimum bid price requirement, the closing bid price of the Company’s common stock must be at least $1 per share for a minimum of ten consecutive business days during this 180 day period. In the event that the Company does not regain compliance within this 180 day period, the Company may be eligible to seek an additional compliance period of 180 calendar days if it meets the continued listing requirement for market value of publicly held shares and all other initial listing standards for the Nasdaq Capital Market, with the exception of the bid price requirement, and provides written notice to Nasdaq of its intent to cure the deficiency during this second compliance period, by effecting a reverse stock split, if necessary. However, if it appears to the Staff that the Company will not be able to cure the deficiency, or if the Company is not otherwise eligible, Nasdaq will provide notice to the Company that its common stock will be subject to delisting.

The Notice does not result in the immediate delisting of the Company’s common stock from The Nasdaq Capital Market. The Company intends to monitor the closing bid price of the Company’s common stock and consider its available options in the event that the closing bid price of the Company’s common stock remains below $1 per share. There can be no assurance that the Company will be able to regain compliance with the minimum bid price requirement or maintain compliance with the other listing requirements.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this Current Report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: January 17, 2020