Sec Form 4 Filing - MILLETT MARK D @ STEEL DYNAMICS INC - 2021-04-29

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person MILLETT MARK D 2. Issuer Name and Ticker or Trading Symbol STEEL DYNAMICS INC [ STLD] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) President and CEO (Last) (First) (Middle) 7575 W. JEFFERSON BLVD. 3. Date of Earliest Transaction (MM/DD/YY) 04/29/2021 (Street) FORT WAYNE, IN46804 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 04/29/2021 G V 19,300 A $ 0 3,330,887 D Common Stock 04/29/2021 G V 19,300 D $ 0 130,700 I By grantor retained annuity trust ( 1 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other MILLETT MARK D 7575 W. JEFFERSON BLVD. FORT WAYNE, IN46804 X President and CEO Signatures Mark D. Millett 04/29/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )On March 24, 2020, the reporting person contributed 150,000 shares of Steel Dynamics, Inc. common stock to a grantor retained annuity trust (GRAT), of which he is the sole trustee and annuitant. constituting a mere change in the form of beneficial ownership, exempt from both the reporting requirements of Section 16(a) and the short-swing profit recovery provisions of Section 16(b) by reason of Rule 16a-13, and entitled to deferred reporting on year-end Form 5. On April 29, 2021, the reporting person, as sole trustee and annuitant under the GRAT, received 19,300 shares of Steel Dynamics, Inc. common stock in partial satisfaction of the GRAT's annuity obligation, constituting a mere change of beneficiary ownership, exempt from both the reporting requirements and short-swing profits provision pursuant to SEC Rule 16a-13. This report is voluntarily made.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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