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 OF SECURITIES 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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(Print or Type Responses)

1. Name and Address of Reporting Person * RINN RUSSELL B   2. Issuer Name and Ticker or Trading Symbol STEEL DYNAMICS INC [STLD] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Executive Vice President (Last) (First) (Middle) 7575 W. JEFFERSON BLVD. 3. Date of Earliest Transaction (Month/Day/Year) 11/21/2017 (Street) FORT WAYNE, IN 46804 4. If Amendment, Date Original Filed(Month/Day/Year) 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 (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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 11/21/2017   A   1,865 (1) A $ 0 139,064 D   Common Stock 11/21/2017   F   870 (2) D $ 37.33 138,194 D   Common Stock 11/21/2017   F   1,839 (3) D $ 37.33 136,355 D   Common Stock 11/21/2017   F   973 (4) D $ 37.33 135,382 D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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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 (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

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 (Month/Day/Year)

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
RINN RUSSELL B 7575 W. JEFFERSON BLVD. FORT WAYNE, IN 46804			Executive Vice President

Signatures

Russell B. Rinn		11/21/2017
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Represents grant of restricted stock, in lieu of restricted stock units because of reporting person's age, for no consideration, and exempt from Section 16(b) by virtue of Rule 16b-3(d)(1) and (3). subject, however, to a two year holding period.
(2)	Represents disposition to issuer to cover taxes payable upon issuance of shares reported in footnote (1), exempt pursuant to Rule 16b-3.
(3)	Represents disposition to issuer to cover taxes payable upon vesting of previously issued and reported restricted stock units, exempt pursuant to Rule 16b-3.
(4)	Represents disposition to issuer to cover taxes payable upon issuance of restricted shares required to be issued to reporting person by reason of his age, in advance of the otherwise applicable second year of the two-year vesting requirement of previously issued restricted stock units; subject however, to an additional one-year holding period.

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