SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE 13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(a)

Under the Securities Exchange Act of 1934

(Amendment No.    )*

MARIN SOFTWARE INCORPORATED

(Name of Issuer)

Common Stock, par value $0.001 per share

(Title of Class of Securities)

56804T205

(CUSIP Number)

Robert B. Ashton
Kinetic Catalyst Partners LLC
6 Occom Ridge
Hanover, NH 03755
(603) 540-2244

With a copy to:

Derek D. Bork

Thompson Hine LLP

3900 Key Center

127 Public Square

Cleveland, Ohio 44114

(216) 566-5500

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

May 10, 2018

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ¨.

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Item 1. Security and Issuer.

This Statement of Beneficial Ownership on Schedule 13D (this “Statement”) relates to the Common Stock, $0.001 par value per share (“Common Stock”), of Marin Software Incorporated, a Delaware corporation (the “Company”). The Company reports that its principal executive offices are located at 123 Mission Street, 27th Floor, San Francisco, California 94105.

Item 2. Identity and Background.

This Statement is filed by Kinetic Catalyst Partners LLC, a Delaware limited liability company (the “Fund”), and Robert B. Ashton.

The Fund and Mr. Ashton are sometimes referred to herein as a “Reporting Person” and collectively as the “Reporting Persons.” The Reporting Persons are filing this Statement jointly. Neither the fact of this filing nor anything contained herein shall be deemed to be an admission by any of the Reporting Persons that they constitute a “group.”

The principal business of the Fund is serving as a private investment fund. The principal occupation of Mr. Ashton is that of private investor and serving as the portfolio manager for the Fund. Mr. Ashton is a U.S. citizen. The business address of each of the Fund and Mr. Ashton is 6 Occom Ridge, Hanover, New Hampshire 03755.

None of the Reporting Persons or any of their partners, managers, officers or other controlling persons has, during the last five years, been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

None of the Reporting Persons or any of their partners, managers, officers or other controlling persons has, during the last five years, been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

Item 3. Source and Amount of Funds or Other Consideration.

The total cost for purchasing the Common Stock reported as owned by the Reporting Persons, including brokerage commissions, was approximately $2,293,000. The source of these funds was working capital of the Fund, Mr. Ashton’s personal funds and funds from trusts and accounts controlled by him.

Item 4. Purpose of Transaction.

On May 17, 2018, the Reporting Persons sent a letter to the Company, which is attached as Exhibit 99.1 hereto and incorporated herein by reference.

The Reporting Persons acquired the shares of Common Stock reported in this Statement for investment purposes. The Reporting Persons may in the future acquire additional shares of Common Stock or dispose of some or all of the shares of Common Stock held by the Reporting Persons in open-market transactions or privately negotiated transactions, on such terms and at such times as the Reporting Persons may deem advisable. The Reporting Persons may engage in short selling or hedging or similar transactions with respect to the shares of Common Stock, on such terms and at such times as the Reporting Persons may deem advisable, subject to applicable law.

The Reporting Persons may engage in discussions with the board and management of the Company regarding its business and affairs. Except as set forth herein or in the letter attached as Exhibit 99.1 hereto, none of the Reporting Persons has any present plan or proposal that would result in any of the actions described in paragraphs (a) through (j) of Item 4 of Schedule 13D. The Reporting Persons reserve the right in the future to formulate any such plans or proposals, and to take any actions with respect to their investments in the Company, including any or all of the actions described in paragraphs (a) through (j) of Item 4 of Schedule 13D.

Item 5. Interest in Securities of the Issuer.

(a) The Reporting Persons beneficially own in the aggregate 294,809 shares of Common Stock, which represents approximately 5.1% of the Company’s outstanding shares of Common Stock.

Each of the Fund and Mr. Ashton holds the number and percentage of shares of Common Stock disclosed as beneficially owned by them in the applicable table set forth on the cover page to this Statement. The Fund holds the 233,118 shares of Common Stock disclosed as beneficially owned by it through KCP II LLC, a Delaware limited liability company. Mr. Ashton has beneficial ownership of 56,891 shares of Common Stock that he holds individually and in an IRA account over which he has sole voting and dispositive power and 4,800 shares of Common Stock that have been gifted to accounts for Mr. Ashton’s children established under the Uniform Transfer to Minors Act and over which shares, as a trustee for such accounts, Mr. Ashton retains the sole voting and dispositive power. In addition, as the portfolio manager for the Fund, Mr. Ashton has the sole power to direct the voting and disposition of the shares of Common Stock beneficially owned by the Fund. Mr. Ashton expressly disclaims beneficial ownership of the Fund’s shares of Common Stock except to the extent of his pecuniary interest therein.

Each percentage ownership of shares of Common Stock set forth in this Statement is based on the 5,751,000 shares of Common Stock reported by the Company as outstanding as of April 30, 2018 in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 11, 2018.

(b) The Fund beneficially owns, and has the sole power to direct the voting and disposition of, the shares of Common Stock disclosed as beneficially owned by the Fund in the applicable table set forth on the cover page to this Statement. Mr. Ashton, as the portfolio manager of the Fund, has the sole power to direct the voting and disposition of the shares of Common Stock held by the Fund. Mr. Ashton expressly disclaims beneficial ownership of the Fund’s shares of Common Stock except to the extent of his pecuniary interest therein. Mr. Ashton has the sole power to direct the voting and disposition of the shares of Common Stock held by Mr. Ashton.

(c) The transactions effected by each of the Reporting Persons in the shares of Common Stock during the past 60 days are set forth on Schedule A to this Statement. Each of these transactions was effected through the open market.

(d) Not applicable.

(e) Not applicable.

Item 6. Contracts, Arrangements, Understandings or Relationships with Respect to Securities of the Issuer.

Information set forth under Item 4 above is incorporated herein by reference.

Pursuant to Rule 13d-1(k) promulgated under the Securities Exchange Act of 1934, as amended, the Reporting Persons have entered into an agreement with respect to the joint filing of this Statement, which agreement is set forth on the signature page to this Statement.

Item 7. Material to Be Filed as Exhibits.

SIGNATURE

After reasonable inquiry and to the best of our knowledge and belief, the undersigned certify that the information set forth in this Statement is true, complete and correct.

In accordance with Rule 13d-1(k)(1)(iii) under the Securities Exchange Act of 1934, as amended, the persons named below agree to the joint filing on behalf of each of them of this Statement on Schedule 13D with respect to the Common Stock of the Company.

Dated: May 17, 2018

Schedule A

Transactions by the Reporting Persons in the Past 60 days

Kinetic Catalyst Partners LLC

Robert B. Ashton

Exhibit 99.1

May 17^th, 2018

The Board of Directors

Marin Software Incorporated

123 Mission St, 27^th Floor

San Francisco, CA 94105

Dear Members of the Board:

I am writing to you on behalf of KCP II LLC and myself which collectively own common stock representing 5.1% of the outstanding stock of Marin Software, making us one of your largest investors.

Since the return of the founder as CEO in August of 2016 we have watched the company repeatedly fail to meet goals for a return to growth and have waited for the board to provide any accountability. Specifically, quarterly revenue has fallen 42% from 24 million in Q3 of 2016 to a projected 14 million in Q2 of 2018. Cash balances have fallen 36% from $36.4 million at the end of Q3 2016 to $23.3 million at the end of Q1 2018. The stock has fallen 68% from $18 to $5.70. Further, the promised inflection point for growth has continually been missed and moved forward.

Summary of conference call statements of return to growth

Given what we believe is the complete failure of the CEO to even remotely meet his own predictions, we have awaited action by the board. Inexplicably, the action the board has recently taken is to reward the management team with stock options, RSUs, and golden parachute agreements. These are assets of shareholders being given to a failed management team by an outside board that has never invested in the stock.

We believe the best course of action is to sell the company. The company’s largest holder, ESW Capital, has acquired over 60 software companies. Their ownership would seem to be a natural starting point for an open and competitive sales process.

Alternatively, if the board does not wish to pursue a sales process, we believe the board would best serve shareholders by voluntarily reconstituting the board with representatives of outside shareholders. Four outside shareholders own 45% of the company and have zero board representation.

The one course of action completely unacceptable is to stay the course. We believe the existing management team and board will destroy remaining shareholder value through continued destruction of the balance sheet and top line revenue.