EXHIBIT 10.1D


                      FOURTH AMENDMENT TO CREDIT AGREEMENT

            THIS FOURTH AMENDMENT TO CREDIT AGREEMENT, dated as of February 20,
2003 (this "Amendment"), is among STEEL DYNAMICS, INC. (the "Borrower"), the
Lenders (as defined below) signatories hereto, JPMORGAN CHASE BANK, as
administrative agent for the Lenders (in such capacity, the "Administrative
Agent"), GENERAL ELECTRIC CAPITAL CORPORATION, as Documentation Agent, and
MORGAN STANLEY SENIOR FUNDING, INC., as Arranger and Syndication Agent.

                              W I T N E S S E T H:

            WHEREAS, the Borrower, certain financial institutions and other
Persons (such capitalized term and other capitalized terms used in these
recitals to have the meanings set forth or defined by reference in Part I below)
from time to time parties thereto (collectively, the "Lenders"), JPMorgan Chase
Bank, as Collateral Agent, the Administrative Agent, General Electric Capital
Corporation, as Documentation Agent, and Morgan Stanley Senior Funding, Inc., as
Arranger and Syndication Agent, are parties to the Credit Agreement, dated as of
March 26, 2002, as amended by the First Amendment to Credit Agreement, dated as
of August 6, 2002, as waived by the Letter Waiver, dated as of October 6, 2002,
as amended by the Second Amendment to Credit Agreement, dated as of December 16,
2002, and as amended by the Third Amendment to Credit Agreement, dated as of
January 23, 2003 (such Credit Agreement, as so amended and waived, the "Existing
Credit Agreement");

            WHEREAS, the Borrower has requested that the Lenders amend the
Existing Credit Agreement as set forth below; and

            WHEREAS, the Lenders have agreed, subject to the terms and
conditions hereinafter set forth, to amend the Existing Credit Agreement in
certain respects (the Existing Credit Agreement, as so amended or otherwise
modified by this Amendment, being referred to as the "Credit Agreement");

            NOW, THEREFORE, in consideration of the premises and for other good
and valuable consideration (the receipt and sufficiency of which is hereby
acknowledged), the parties hereto hereby agree as follows:

                                    PART I
                                  DEFINITIONS

            SUBPART 1.1. Certain Definitions. The following terms (whether or
not underscored) when used in this Amendment shall have the following meanings
(such meanings to be equally applicable to the singular and plural forms
thereof):

            "Administrative Agent" is defined in the preamble.

            "Amendment" is defined in the preamble.

            "Borrower" is defined in the preamble.

            "Credit Agreement" is defined in the third recital.

            "Existing Credit Agreement" is defined in the first recital.

            "Fourth Amendment Effective Date" is defined in Subpart 3.1.

            "Lenders" is defined in the first recital.

            SUBPART 1.2. Other Definitions. Terms for which meanings are
provided in the Existing Credit Agreement are, unless otherwise defined herein
or the context otherwise requires, used in this Amendment with such meanings.

                                    PART II
                                   AMENDMENTS

            Effective on (and subject to the occurrence of) the Fourth Amendment
Effective Date, the Existing Credit Agreement is hereby amended in accordance
with this Part; except as so amended or otherwise modified by this Amendment,
the Existing Credit Agreement and the Loan Documents shall continue in full
force and effect in accordance with their terms.

            SUBPART 2.1. Amendment to Article I. Article I of the Existing
Credit Agreement is hereby amended in accordance with Subparts 2.1.1 and 2.1.2.

                  SUBPART 2.1.1. Section 1.01 of the Existing Credit Agreement
      is hereby amended by deleting the phrase "(other than the Capital
      Expenditures referred to in clauses (i) and (ii) of the proviso to Section
      5.02(p))" appearing in clause (iv) of the definition of "Fixed Charge
      Coverage Ratio" and inserting in replacement therefor the phrase "(other
      than the Capital Expenditures referred to in clauses (i) and (ii) of the
      first proviso to Section 5.02(p) and the Capital Expenditures referred to
      in the second proviso to Section 5.02(p))."

                  SUBPART 2.1.2. Section 1.01 of the Existing Credit Agreement
      is hereby further amended by inserting the following new definitions
      therein in the appropriate alphabetical order:

                  "Fourth Amendment" means the Fourth Amendment, dated as of
            February 20, 2003, to this Agreement among the Borrower, the
            Administrative Agent, Morgan Stanley Senior Funding, Inc. and the
            Lenders parties thereto.

                  "Fourth Amendment Effective Date" is defined in Subpart 3.1 of
            the First Amendment.

                  "GalvPro Acquisition" means the acquisition by the Borrower of
            all of the assets of a cold rolled galvanizing facility in
            Jeffersonville, Indiana (the "GalvPro Facility") from GalvPro II
            LLC, all as described in the GalvPro Asset Purchase Agreement.


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                  "GalvPro Asset Purchase Agreement" means the asset purchase
            agreement dated as of January 28, 2003 between the Borrower, as
            Buyer, GalvPro II LLC, as Seller, and ING Capital LLC.

                  "GalvPro Facility" has the meaning set forth therefor in the
            definition of "GalvPro Acquisition" above.

                  "GalvPro Sublease" means that certain sublease by and between
            GalvPro II LLC and the City of Jeffersonville acting by and through
            the Jefferson Redevelopment Commission, as lessor, dated December
            10, 1999 and recorded December 13, 1999 as Instrument No. 26530,
            Miscellaneous Drawer 31, in the Clark County, Indiana Recorders'
            Office, which sublease will be assigned by GalvPro II LLC to the
            Borrower as set forth in the GalvPro Asset Purchase Agreement.

                  "Jeffersonville TIF Bonds" means the Jeffersonville
            Redevelopment Authority Tax Increment Lease Revenue Bonds of 1999 in
            the outstanding principal amount of $1,075,000 which will be
            acquired by the Borrower from GalvPro II LLC as set forth in the
            GalvPro Asset Purchase Agreement.

            SUBPART 2.2. Amendment to Article V. Article V of the Existing
Credit Agreement is hereby amended in accordance with Subparts 2.2.1 through
2.2.3.

                  SUBPART 2.2.1. Clause (f) of Section 5.02 of the Existing
      Credit Agreement is hereby amended by (a) deleting the punctuation mark
      "." appearing at the end of sub-clause (xii) thereof and inserting the
      punctuation mark ";" in replacement therefor and (b) inserting at the end
      thereof the following new sub-clauses (xiii) and (xiv):

            "(xiii) the GalvPro Acquisition; and

            (xiv) the Jeffersonville TIF Bonds."

                  SUBPART 2.2.2. Clause (h) of Section 5.02 of the Existing
      Credit Agreement is hereby amended by (a) deleting the punctuation mark
      "." appearing at the end thereof and inserting the punctuation mark "," in
      replacement therefor and (b) inserting at the end thereof the following
      phrase:

                  "and other than (and exclusive of obligations payable under)
            the GalvPro Sublease ".

                  SUBPART 2.2.3. Clause (p) of Section 5.02 of the Existing
      Credit Agreement is hereby amended by inserting at the end thereof the
      following new proviso:

                  "and provided further, however, that for the Fiscal Year
            ending on December 31, 2003, additional Capital Expenditures of no
            more than $25,000,000 in the aggregate may be made with respect to
            the acquisition of, and improvements to, the GalvPro Facility."


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                                    PART III
                          CONDITIONS TO EFFECTIVENESS

            SUBPART 3.1. Effectiveness. This Amendment and the amendments
contained herein shall become effective on the date (the "Fourth Amendment
Effective Date") when each of the conditions set forth in this Part shall have
been fulfilled to the satisfaction of the Administrative Agent, provided that
such conditions are in any event fulfilled no later than February 28, 2003.

                  SUBPART 3.1.1. Execution of Counterparts. The Administrative
      Agent and the Arranger shall have received counterparts of this Amendment,
      duly executed and delivered on behalf of the Borrower, the Administrative
      Agent and the Required Lenders.

                  SUBPART 3.1.2. Amendment Fee. The Administrative Agent shall
      have received, for the account of each Lender which shall have executed
      this Amendment before 5:00 p.m. (New York time) on February 20, 2003, an
      amendment fee in an aggregate amount equal to .05% of the aggregate amount
      of each such Lender's Advances and Commitments.

                  SUBPART 3.1.3. Expenses. The Borrower shall have paid all
      expenses (including the fees and expenses of Shearman & Sterling) incurred
      in connection with the preparation, negotiation and execution of this
      Amendment and other matters relating to the Credit Agreement from and
      after the last invoice to the extent invoiced.

                  SUBPART 3.1.4. Legal Details, etc. All documents executed or
      submitted pursuant hereto shall be satisfactory in form and substance to
      the Administrative Agent and the Arranger and Shearman & Sterling as
      counsel. The Administrative Agent, the Arranger and counsel shall have
      received all information and such counterpart originals or such certified
      or other copies or such materials as the Administrative Agent, the
      Arranger or counsel may reasonably request, and all legal matters incident
      to the transactions contemplated by this Amendment shall be satisfactory
      to the Administrative Agent, the Arranger and counsel.

                                    PART IV
                  MISCELLANEOUS; REPRESENTATIONS AND COVENANTS

            SUBPART 4.1. Continuing Effectiveness, etc. As amended hereby, the
Credit Agreement shall remain in full force and effect and is hereby ratified
and confirmed in all respects. After the Fourth Amendment Effective Date, all
references in the Credit Agreement and each other Loan Document to the
"Agreement" or "Credit Agreement", as applicable, shall refer to the Existing
Credit Agreement, after giving effect to this Amendment, and this Amendment
shall be a Loan Document for all purposes. The Borrower hereby confirms its
obligations under Section 8.04 of the Credit Agreement to pay all fees and
expenses of the Administrative Agent and the Arranger (including reasonable fees
and out-of-pocket expenses of Shearman & Sterling) in connection with this
Amendment and other ongoing administration of the Credit Agreement as provided
in Section 8.04 of the Credit Agreement since the last invoice it received.


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                  SUBPART 4.2. Give Security. (a) The Borrower hereby confirms
      its obligations under Section 5.01(j) of the Credit Agreement to give
      security in connection and with respect to the GalvPro Acquisition as such
      obligations are described in Section 5.01(j) of the Credit Agreement.

      (b)   The Borrower hereby agrees to provide to the Collateral Agent within
45 days after the consummation of the GalvPro Acquisition (or 60 days, in the
case of clause (vii) below), the following:

            (i)    a leasehold mortgage upon the real estate and improvements to
      be acquired by the Borrower in Clark County, Indiana in connection with
      the GalvPro Acquisition in form and substance reasonably satisfactory to
      the Collateral Agent;

            (ii)   evidence that the leasehold mortgage referred to in
      subparagraph (i) above has been duly recorded in the appropriate recording
      offices and that all filing and recording taxes and fees have been paid;

            (iii)  a mortgage loan title insurance policy insuring the leasehold
      mortgage referred to in subparagraph (i) above in an amount acceptable to
      the Collateral Agent issued by a title insurance company of recognized
      standing reasonably satisfactory to the Collateral Agent ("Title Insurance
      Company") and in form and substance reasonably satisfactory to the
      Collateral Agent, along with such reinsurance and direct access agreements
      as the Collateral Agent may deem necessary or desirable;

            (iv)   a survey in form and substance reasonably satisfactory to the
      Collateral Agent, certified to the Collateral Agent and the Title
      Insurance Company pursuant to a certification reasonably satisfactory to
      the Collateral Agent;

            (v)    a favorable opinion of Barrett & McNagny, LLP, local counsel
      to the Lender Parties, in form and substance reasonably satisfactory to
      the Collateral Agent;

            (vi)   evidence of the insurance required by the terms of the
      mortgage referred to in subparagraph (i) above;

            (vii)  to the extent reasonably required by the Collateral Agent,
      estoppel and consent agreements executed by any lessors or sublessors
      under the GalvPro Sublease and the primary lease governing the GalvPro
      Sublease, all in form and substance satisfactory to Collateral Agent; and

            (viii) such other assignments, security agreements and other
      documents as may be reasonably required by the Collateral Agent to obtain
      and perfect liens and security interests for the benefit of the Lender
      Parties in the assets acquired by the Borrower pursuant to the GalvPro
      Acquisition.

      (c)   The Borrower hereby agrees to provide to the Collateral Agent within
45 days after the acquisition of a fee interest in the GalvPro Facility, the
following:


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            (i)   a mortgage upon the real estate and improvements acquired by
      the Borrower in connection with the GalvPro Facility in form and substance
      reasonably satisfactory to the Collateral Agent;

            (ii)  evidence that the mortgage referred to in subparagraph (i)
      above has been duly recorded in the appropriate recording offices and that
      all filing and recording taxes and fees have been paid;

            (iii) a mortgage loan title insurance policy insuring the mortgage
      referred to in subparagraph (i) above in an amount acceptable to the
      Collateral Agent issued by the Title Insurance Company and in form and
      substance reasonably satisfactory to the Collateral Agent, along with such
      reinsurance and direct access agreements as the Collateral Agent may deem
      necessary or desirable;

            (iv)  a survey in form and substance reasonably satisfactory to the
      Collateral Agent, certified to the Collateral Agent and the Title
      Insurance Company pursuant to a certification reasonably satisfactory to
      the Collateral Agent;

            (v)   a favorable opinion of Barrett & McNagny, LLP, local counsel
      to the Lender Parties, in form and substance reasonably satisfactory to
      the Collateral Agent;

            (vi)  evidence of the insurance required by the terms of the
      mortgage referred to in subparagraph (i) above; and

            (vii) such other assignments, security agreements and other
      documents as may be reasonably required by the Collateral Agent to obtain
      and perfect liens and security interests for the benefit of the Lender
      Parties in the assets acquired by the Borrower in connection with the
      GalvPro Facility.

            SUBPART 4.3. Counterparts. This Amendment may be executed in any
number of counterparts and by the different parties on separate counterparts,
and each such counterpart shall be deemed to be an original but all such
counterparts shall together constitute one and the same Amendment.

            SUBPART 4.4. Governing Law. THIS AMENDMENT SHALL BE A CONTRACT MADE
UNDER AND GOVERNED BY THE INTERNAL LAWS OF THE STATE OF NEW YORK.

            SUBPART 4.5. Successors and Assigns. This Amendment shall be binding
upon the Borrower, the Lenders and the Agents and their respective successors
and assigns, and shall inure to their successors and assigns.

            SUBPART 4.6. Representations and Warranties; Event of Default. In
order to induce the Lenders to execute and deliver this Amendment, (a) the
Borrower represents and warrants to the Agents, the Lenders and the Issuing Bank
that, after giving effect to the terms of this Amendment, the following
statements are true and correct: (i) the representations and warranties set
forth in Article IV of the Existing Credit Agreement and in the other Loan
Documents are true and correct on the Fourth Amendment Effective Date as if made
on the


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Fourth Amendment Effective Date and after giving effect to the Fourth Amendment
(unless stated to relate solely to an earlier date, in which case such
representations and warranties were true and correct in all material respects as
of such earlier date); (ii) no Default has occurred and is continuing; and (iii)
the GalvPro Asset Purchase Agreement contains unqualified representations and
warranties from the seller thereunder providing that the consummation of such
acquisition will not violate or otherwise breach agreements to which such seller
is a party and (b) the Borrower agrees that any breach in any material respect
of any representation, warranty, or covenant contained in this Amendment shall
constitute an Event of Default.

            SUBPART 4.7. Modifications to this Amendment. This Amendment can be
amended, waived or otherwise modified by instrument in writing signed by the
Borrower and the Required Lenders.

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            IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be executed and delivered by their respective authorized officers as of the day
and year first above written.

                                          STEEL DYNAMICS, INC.


                                          By: /s/ THERESA E. WAGLER
                                              ---------------------------
                                              Title: ASSISTANT SECRETARY



                                          JPMORGAN CHASE BANK,
                                            as Administrative Agent and
                                                Collateral Agent and as a Lender

                                          By: /S/  JAMES H. RAMAGE
                                              ---------------------------------
                                              Title: MANAGING DIRECTOR



                                         MORGAN STANLEY SENIOR FUNDING, INC.,
                                            as Arranger and Syndication Agent
                                                and as a Lender


                                          By: /S/ JAAP L. TONCKENS
                                             ----------------------------------
                                              Title: VICE PRESIDENT



                                         GENERAL ELECTRIC CAPITAL CORPORATION,
                                            as Documentation Agent and as a
                                                Lender


                                          By: /S/ ILLEGIBLE
                                             ----------------------------------
                                              Title: DULY AUTHORIZED SIGNATORY