Ducommun (DCO) DEFA14A Additional proxy soliciting materials

SCHEDULE 14A INFORMATION

(RULE 14A-101)

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SCHEDULE 14A INFORMATION

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*** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to Be Held on May 01, 2019 DUCOMMUN INCORPORATED DUCOMMUN INCORPORATED 200 SANDPOINTE AVENUE, #700 SANTA ANA, CA 92707 ATTN: RAJIV TATA Meeting Information Meeting Type: Annual Meeting For holders as of: March 04, 2019 Date: May 01, 2019 Time: 9:00 AM PDT Location: Courtyard Marriott Santa Ana 8 MacArthur Place Santa Ana, CA 92707 You are receiving this communication because you hold shares in the above named company. This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of 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. See the reverse side of this notice to obtain proxy materials and voting instructions. 0000406643_1 R1.0.1.18

Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE: 1. Annual Report 2. Notice & Proxy Statement How to View Online: Have the information that is printed in the box marked by the arrow (located on the following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER orE-MAIL Copy: If you want to receive a paper ore-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) BYE-MAIL*: sendmaterial@proxyvote.com * If requesting materials bye-mail, please send a blanke-mail with the information that is printed in the box marked by the arrow (located on the following page) in the subject line. Requests, instructions and other inquiries sent to thise-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before April 17, 2019 to facilitate timely delivery. How To Vote Please Choose One of the Following Voting Methods 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 box marked by the arrow available and follow the instructions. Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. 0000406643_2 R1.0.1.18

Voting items The Board of Directors recommends a vote FOR the nominees listed: 1. Election of Directors Nominees 01 Robert C. Ducommun 02 Dean M. Flatt 03 Jay L. Haberl and The Board of Directors recommends a vote FOR Proposals 2 and 3. 2. Advisory resolution on executive compensation. 3. Ratification of the selection of PricewaterhouseCoopers LLP as the Company’s Independent Registered Public Accounting Firm for 2019. NOTE: In their discretion, the Proxies are authorized to vote upon such other business as may properly come before the meeting or any adjournment thereof. 0000406643_3 R1.0.1.18

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