UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 14A
Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934 (Amendment No. )
Filed by the Registrant  x
Filed by a Party other than the Registrant  o
Check the appropriate box:
o	Preliminary Proxy Statement
o	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))
o	Definitive Proxy Statement
x	Definitive Additional Materials
o	Soliciting Material under §240.14a-12
Steel Dynamics, 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):
x	No fee required.
o	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:
o	Fee paid previously with preliminary materials.
o	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 Stockholder Meeting to Be Held on May 17, 2018 STEEL DYNAMICS, INC. Meeting Information Meeting Type: Annual Meeting For holders as of: March 19, 2018 Date: May 17, 2018 Location: Grand Wayne Center Time: 9:00 AM EDT 0000369783_1 R1.0.1.17 7575 WEST JEFFERSON BLVD. FORT WAYNE, IN 46804 120 West Jefferson Boulevard Fort Wayne, Indiana 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.

Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE: 1. Notice & Proxy Statement2. Form 10-K3. Annual Report Have the information that is printed in the box marked by the arrow following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER or E-MAIL Copy: (located on the 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 by the arrow (located on the following page) in the subject line. 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 03, 2018 to facilitate timely delivery. How To Vote Please Choose One of the Following Voting Methods Vote In Person: Many stockholder 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. 0000369783_2 R1.0.1.17

0000369783_3 R1.0.1.17 The Board of Directors recommends you vote FOR the following: 1. Election of Directors Nominees The Board of Directors recommends you vote FOR proposals 2, 3, 4 and 5. 2TO APPROVE THE APPOINTMENT OF ERNST & YOUNG LLP AS STEEL DYNAMICS INC.'S INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM FOR THE YEAR 2018 3TO APPROVE AN AMENDMENT TO STEEL DYNAMICS INC.'S AMENDED AND RESTATED ARTICLES OF INCORPORATION TO PROVIDE BY A MAJORITY VOTE THAT STOCKHOLDERS MAY AMEND THE STEEL DYNAMICS INC.'S BYLAWS 4TO HOLD AN ADVISORY VOTE TO APPROVE THE COMPENSATION OF THE NAMED EXECUTIVE OFFICERS 5TO APPROVE THE STEEL DYNAMICS, INC. 2018 EXECUTIVE INCENTIVE COMPENSATION PLAN NOTE: Unless otherwise directed, this proxy will be voted "FOR" the nominees listed in Proposal 1, and "For" Proposals 2, 3, 4 and 5.

0000369783_4 R1.0.1.17