Ownership Submission
FORM 5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
Form 3 Holdings Reported
Form 4 Transactions Reported
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

ANNUAL 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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1. Name and Address of Reporting Person *
MARCUCCILLI JAMES C
 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
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)

127 WEST BERRY STREET		 3. Statement for Issuer's Fiscal Year Ended (Month/Day/Year)
12/31/2011
(Street)


FORT WAYNE, IN 46802		 4. If Amendment, Date Original Filed(Month/Day/Year)
 6. Individual or Joint/Group Reporting
(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 at end of Issuer's Fiscal Year
(Instr. 3 and 4)		 6. Ownership Form: Direct (D) or Indirect (I)
(Instr. 4)		 7. Nature of Indirect Beneficial Ownership
(Instr. 4)
Amount (A) or (D) Price

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number. SEC 2270 (9-02)

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 at End of Issuer's Fiscal Year
(Instr. 4)		 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 4)		 11. Nature of Indirect Beneficial Ownership
(Instr. 4)
(A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
Deferred Stock Units $ 0 06/30/2011 06/30/2011 A 33 (1)     (2)   (2) Common Stock
33
$ 0 5,297 (3)
D
 
Deferred Stock Units $ 0 09/30/2011 09/30/2011 A 48 (1)     (2)   (2) Common Stock
48
$ 0 5,345 (3)
D
 
Deferred Stock Units $ 0 12/30/2011 12/30/2011 A 36 (1)     (2)   (2) Common Stock
36
$ 0 5,381 (3)
D
 

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
MARCUCCILLI JAMES C
127 WEST BERRY STREET
FORT WAYNE, IN 46802		   X      

Signatures

James C. Marcuccilli 02/15/2011
**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) Exempt award, pursuant to registrant's 2006 Equity Incentive Plan, of 33 additional Deferred Stock Units (DSUs) on June 30, an additional 48 on September 30 and an additional 36 on December 31, 2011, determined by dividing the dollar amount of deemed dividends on each of the foregoing dates, issued in respect of reporting person's underlying 5,264 DSUs originally awarded June 1, 2011 and previously reported on Form 4 on June 3, 2011, divided by the closing price of Issuer's common stock on the day preceding each dividend record date.
(2) The reporting person, by prior election, chose to receive his common stock, when converted from DSUs, at the expiration of one year following the reporting person's termination of service as a director.
(3) Totals shown on each line include the same 5,264 originally issued DSUs plus the cumulative additional DSUs issued in respect of the deemed dividend following each dividend date.

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