*** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Stockholder Meeting to Be Held on May 08, 2020 STEEL DYNAMICS, INC. 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. 7575 WEST JEFFERSON BLVD. FORT WAYNE, IN 46804 0000450309_1 R1.0.1.18 See the reverse side of this notice to obtain proxy materials and voting instructions. Meeting Information Meeting Type: Annual Meeting For holders as of: March 09, 2020 Date: May 08, 2020Time: 9:00 AM EDT Location: Courtyard by Marriott 1150 South Harrison Street Fort Wayne, Indiana 46802

Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE:  Have the information that is printed in the box marked by the arrow (located on the  by the arrow (located on the following page) in the subject line. How To Vote Please Choose One of the Following Voting Methods possession  available and follow the instructions. marked by the arrow 0000450309_2 R1.0.1.18 Vote In Person: Many stockholder meetings have attendance requirements including, but not limited to, the of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any specia 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 Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. l 1. Notice & Proxy Statement2. Form 10-K3. Annual Report 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 April 23, 2020 to facilitate timely delivery.

The Board of Directors recommends you vote FOR the following: 1. Election of Directors Nominees 01 06 11 Mark D. Millett Traci M. Dolan Richard P. Teets, Jr. 02 Sheree L. Bargabos 07 James C. Marcuccilli 03 Keith E. Busse 08 Bradley S. Seaman 04 Frank D. Byrne, M.D. 09 Gabriel L. Shaheen 05 Kenneth W. Cornew 10 Steven A. Sonnenberg The Board of Directors recommends you vote FOR proposals 2 and 3. 2TO APPROVE THE APPOINTMENT OF ERNST & YOUNG LLP AS STEEL DYNAMICS INC.'S INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR THE YEAR 2020 3TO HOLD AN ADVISORY VOTE TO APPROVE THE COMPENSATION OF THE NAMED EXECUTIVE OFFICERS NOTE: Unless otherwise directed, this proxy will be voted "FOR" the nominees listed in Proposal 1, and "For" Proposals 2 and 3. 0000450309_3 R1.0.1.18 Voting items

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