Filed by the Registrant ☒

Filed by a Party other than the Registrant ☐

Check the appropriate box:

☐

Preliminary Proxy Statement

☐

Confidential, for Use of the Commission Only (as permitted by Rule 14a‑6(e)(2))

☐

Definitive Proxy Statement

☒

Definitive Additional Materials

☐

Soliciting Material Pursuant to §240.14a‑12

AXT, Inc.

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

☒

No fee required.

☐

Fee computed on table below per Exchange Act Rules 14a‑6(i)(1) and 0-11.

(1)

Title of each class of securities to which transaction applies:

(2)

Aggregate number of securities to which transaction applies:

(3)

Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0‑11 (set forth the amount on which the filing fee is calculated and state how it was determined):

(4)

Proposed maximum aggregate value of transaction:

(5)

Total fee paid:

☐

Fee paid previously with preliminary materials.

Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the

☐

Form or Schedule and the date of its filing.

(1)

Amount Previously Paid:

(2)

Form, Schedule or Registration Statement No.:

(3)

Filing Party:

(4)

Date Filed:

*** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to Be Held on May 26, 2016. AXT, INC. You are receiving this communication because you hold shares in the company named above. This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of C/O BROADRIDGE P.O. BOX 1342 BRENTWOOD, NY 11717 the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side). We encourage you to access and review all of the important information contained in the proxy materials before voting. proxy materials and voting instructions. E08104-P78334 See the reverse side of this notice to obtain Meeting Information Meeting Type:Annual Meeting For holders as of:April 1, 2016 Date: May 26, 2016Time: 11:00 AM PDT Location: 4281 Technology Drive Fremont, CA 94538

Before You Vote How to Access the Proxy Materials Have the information that is printed in the box marked by the arrow XXXX XXXX XXXX XXXX (located on the by the arrow XXXX XXXX XXXX XXXX (located on the following page) in the subject line. How To Vote Please Choose One of the Following Voting Methods box marked by the arrow XXXX XXXX XXXX XXXX (located on the following page) available and follow the instructions. E08105-P78334 Vote In Person: Many shareholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares. Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. Proxy Materials AAvvaaiillaabbllee ttooVVIEIEWWoorrRREECCEEIVIVEE: : 1. Notice and Proxy Statement2. Annual Report on Form 10-K How to View Online: following page) and visit: www.proxyvote .com. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET:www.proxyvote.com 2) BY TELEPHONE: 1-800-579-1639 3) BY E-MAIL*:sendmaterial@proxyvote.com * If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before May 12, 2016 to facilitate timely delivery.

The Board of Directors recommends you vote FOR the following: 1. To elect One (1) Class III Director to hold office for a three-year term and until his successor is elected and qualified. Class III Director: 01) Leonard J. LeBlanc The Board of Directors recommends you vote FOR proposals 2 and 3. 2. To approve, on an advisory basis, the compensation of AXT's named executive officers. 3. To ratify the appointment of Burr Pilger Mayer, Inc. as AXT's independent registered public accounting firm for the fiscal year ending December 31, 2016. NOTE: Such other business as may properly come before the meeting or any adjournment thereof. E08106-P78334 Voting Items

c/o BROADRIDGE P.O. BOX 1342 BRENTWOOD, NY 11717

VOTE BY INTERNET - www.proxyvote.com Use the Internet to transmit your voting instructions and for electronic delivery of information up until 11:59 P.M. Eastern Time the day before the cut-off date or meeting date. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form.

ELECTRONIC DELIVERY OF FUTURE PROXY MATERIALS If you would like to reduce the costs incurred by our company in mailing proxy materials, you can consent to receiving all future proxy statements, proxy cards and annual reports electronically via e-mail or the Internet. To sign up for electronic delivery, please follow the instructions above to vote using the Internet and, when prompted, indicate that you agree to receive or access proxy materials electronically in future years.

VOTE BY PHONE - 1-800-690-6903 Use any touch-tone telephone to transmit your voting instructions up until 11:59 P.M. Eastern Time the day before the cut-off date or meeting date. Have your proxy card in hand when you call and then follow the instructions.

VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717.

TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: E08099-P78334 KEEP THIS PORTION FOR YOUR RECORDS DETACH AND RETURN THIS PORTION ONLY THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. To withhold authority to vote for any individual nominee(s), mark “For All Except” and write the number(s) of the nominee(s) on the line below. AXT, INC. The Board of Directors recommends you vote FOR the following: For Withhold For All AllAllExcept  ! ! ! 1. To elect One (1) Class III Director to hold office for a three-year term and until his successor is elected and qualified. Class III Director: 01) Leonard J. LeBlanc For Against Abstain The Board of Directors recommends you vote FOR proposals 2 and 3. ! ! ! ! ! ! 2. To approve, on an advisory basis, the compensation of AXT's named executive officers. 3. To ratify the appointment of Burr Pilger Mayer, Inc. as AXT's independent registered public accounting firm for the fiscal year ending December 31, 2016. NOTE: Such other business as may properly come before the meeting or any adjournment thereof. For address change/comments mark here. (see reverse for instructions) ! ! Yes ! No Please indicate if you plan to attend this meeting. Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name by authorized officer. Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date

Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting: The Notice and Proxy Statement and Annual Report on Form 10-K are available at www.proxyvote.com.

AXT, INC. Annual Meeting of Stockholders May 26, 2016 11:00 a.m. This proxy is solicited by the Board of Directors The undersigned hereby constitutes and appoints Morris S. Young and Gary L. Fischer and each of them, as his or her true and lawful agents and proxies with full power of substitution and hereby authorizes them to represent the undersigned and to vote all of the shares of common stock in AXT, Inc., which the undersigned is entitled to vote at the 2016 Annual Meeting of Stockholders to be held at 4281 Technology Drive, Fremont, California on May 26, 2016 at 11:00 a.m. Pacific Daylight Time, and at any adjournment thereof (1) as hereinafter specified upon the proposals listed and as more particularly described in AXT's proxy statement, receipt of which is hereby acknowledged and (2) in their discretion upon such other matters as may properly come before the meeting. This proxy, when properly executed, will be voted in the manner directed herein. If no such direction is made, this proxy will be voted in accordance with the Board of Directors' recommendations. (If you noted any Address Changes and/or Comments above, please mark corresponding box on the reverse side.) Continued and to be signed on reverse side Address change/comments: