UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 3)*

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 section 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).

*Reflects (i) 4,765,357 shares of common stock, par value $0.0001 per share (the “Common Stock”) of the Issuer (as defined below) and 447,255 shares of Common Stock underlying stock options that may be exercised by the Reporting Person (as defined below) within 60 days of the date hereof.

**Percentage calculated based on 63,580,470 shares of Common Stock as of November 1, 2018 as disclosed in the Issuer’s Form 10-Q filed on November 8, 2018 with the Securities and Exchange Commission, plus the 447,255 shares of Common Stock underlying stock options that may be exercised by the Reporting Person within 60 days of the date hereof.

Explanatory Note

This Amendment No. 3 to the statement on Schedule 13D amends and supplements the statement on Schedule 13D filed by Thomas C. Shay (the “Reporting Person”) on October 23, 2017 (the “Original Schedule 13D”), as amended on June 22, 2018 and July 20, 2018 (such Original Schedule 13D, as amended, the “Schedule 13D”). Terms defined in the Original Schedule 13D are used herein as defined.

Item 2(c) is amended and restated in its entirety as follows:

(c)       Effective as of January 31, 2019, the Reporting Person resigned as a member of the Issuer’s Board of Directors and as Corporate Secretary and, effective on or about February 8, 2019, is scheduled to retire as an employee and executive officer of the Issuer.

The Reporting Person may be deemed to beneficially own 5,212,612 shares of Common Stock, which include 447,255 shares of Common Stock underlying stock options exercisable within 60 days of the date hereof held directly by the Reporting Person.

Item 4 is amended and restated in its entirety as follows:

The Reporting Person received shares of Common Stock of the Issuer in connection with its 2017 merger as described in Item 3 of the Original Schedule 13D.

As an executive officer and employee of the Issuer, Mr. Shay has received option grants pursuant to certain equity compensation arrangements generally applicable to the Issuer’s employees as disclosed in the Issuer’s Proxy Statements on Schedule 14A filed with the SEC and pursuant to agreements entered into in connection with such equity compensation plans, the forms of which have been filed with the SEC by the Issuer.

The information set forth in Item 2(c), above, is incorporated by reference into this Item 4.

The Reporting Person intends to continue to evaluate his ownership and voting position in the Issuer and may continue to hold his equity position in the Issuer, acquire additional securities of the Issuer or may dispose of his equity position in the Issuer in the future. 

Except as set forth herein, the Reporting Person (in his capacity as stockholder of the Issuer) has no present intent or proposals that relate to or would result in any of the transactions or other matters specified in clauses (a) through (j) of Item 4 of Schedule 13, provided that the Reporting Person may, at any time, review or reconsider his position with respect to the Issuer and reserves the right to develop such plans or proposals in the future.

Item 5(c) is amended and restated in its entirety:

The information contained in Exhibit 99.1 hereto is incorporated by reference into this Item 5(c).

The information set forth in Item 4, above, is incorporated by reference into this Item 6.

The following exhibits are filed herewith:

SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: February 1, 2019

Exhibit 24.1

POWER OF ATTORNEY

(For Executing Schedule 13D)

Know all by these presents, that the undersigned hereby constitutes and appoints each of Daniel B. Winslow, Andrew J. Terry and Celeste Rasmussen Peiffer of Rimini Street, Inc. (the “Company”), signing individually, the undersigned’s true and lawful attorneys-in-fact and agents to:

The undersigned hereby grants to such attorney-in-fact full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact's substitute or substitutes, shall lawfully do or cause to be done by virtue of this power of attorney and the rights and powers herein granted. The undersigned acknowledges that the foregoing attorney-in-fact, and their substitutes, in serving in such capacity at the request of the undersigned, are not assuming (nor is the Company assuming) any of the undersigned’s responsibilities to comply with Section 13(d) of the Exchange Act, which remains the responsibility of the undersigned in full.

This Power of Attorney shall remain in full force and effect until the earliest to occur of (a) the undersigned is no longer required to file Schedule 13D (including amendments thereto) in respect of the undersigned’s holdings of and transactions in securities issued by the Company following any “exit” filing in respect thereof, (b) revocation by the undersigned in a signed writing delivered to the Company and the foregoing attorneys-in-fact or (c) as to any attorney-in-fact individually, until such attorney-in-fact is no longer employed by the Company.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of the date written below.

Date: February 1, 2019

Exhibit 99.1

TRANSACTIONS IN THE ISSUER’S SECURITIES DURING THE LAST 60 DAYS

During the last 60 days, the Reporting Person has sold an aggregate 30,000 shares of the Issuer’s Common Stock pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person, as follows: