Document:

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                                                                   EXHIBIT 10.2a

                         SUBSIDIARY GUARANTY SUPPLEMENT

                                                                   April 7, 2002

JPMorgan Chase Bank, as Administrative Agent
270 Park Avenue
New York, New York  10017
Attention:  James Ramage

               Credit Agreement dated as of March 26, 2002 among
Steel Dynamics, Inc, an Indiana corporation (the "BORROWER"), the Lender Parties
   party to the Credit Agreement, JP MORGAN CHASE BANK, as Collateral Agent,
        JPMorgan Chase Bank, as Administrative Agent, and Morgan Stanley
            Senior Funding, Inc., as Arranger and Syndication Agent

Ladies and Gentlemen:

            Reference is made to the above-captioned Credit Agreement and to the
Subsidiary Guaranty referred to therein (such Subsidiary Guaranty, as in effect
on the date hereof and as it may hereafter be amended, supplemented or otherwise
modified from time to time, together with this Guaranty Supplement, being the
"SUBSIDIARY GUARANTY"). The capitalized terms defined in the Subsidiary Guaranty
or in the Credit Agreement and not otherwise defined herein are used herein as
therein defined.

            Section 1. Guaranty; Limitation of Liability. (a) The undersigned
hereby absolutely, unconditionally and irrevocably guarantee the punctual
payment when due, whether at scheduled maturity or on any date of a required
prepayment or by acceleration, demand or otherwise, of all Obligations of each
other Loan Party now or hereafter existing under or in respect of the Loan
Documents (including, without limitation, any extensions, modifications,
substitutions, amendments or renewals of any or all of the foregoing
Obligations), whether direct or indirect, absolute or contingent, and whether
for principal, interest, premium, fees, indemnities, contract causes of action,
costs, expenses or otherwise (such Obligations being the "GUARANTEED
OBLIGATIONS"), and agree to pay any and all expenses (including, without
limitation, fees and expenses of counsel) incurred by the Administrative Agent
or any other Secured Party in enforcing any rights under this Guaranty
Supplement, the Subsidiary Guaranty or any other Loan Document. Without limiting
the generality of the foregoing, the undersigned's liability shall extend to all
amounts that constitute part of the Guaranteed Obligations and would be owed by
any other Loan Party to any Secured Party under or in respect of the Loan
Documents but for the fact that they are unenforceable or not allowable due to
the existence of a bankruptcy, reorganization or similar proceeding involving
such other Loan Party.

            (b) The undersigned, and by its acceptance of this Guaranty
Supplement, the Administrative Agent and each other Secured Party, hereby
confirm that it is the intention of all such Persons that this Guaranty
Supplement, the Subsidiary Guaranty and the Obligations of the
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undersigned hereunder and thereunder not constitute a fraudulent transfer or
conveyance for purposes of Bankruptcy Law, the Uniform Fraudulent Conveyance
Act, the Uniform Fraudulent Transfer Act or any similar foreign, federal or
state law to the extent applicable to this Guaranty Supplement, the Subsidiary
Guaranty and the Obligations of the undersigned hereunder and thereunder. To
effectuate the foregoing intention, the Administrative Agent, the other Secured
Parties and the undersigned hereby irrevocably agree that the Obligations of the
undersigned under this Guaranty Supplement and the Subsidiary Guaranty at any
time shall be limited to the maximum amount as will result in the Obligations of
the undersigned under this Guaranty Supplement and the Subsidiary Guaranty not
constituting a fraudulent transfer or conveyance.

            (c) The undersigned hereby unconditionally and irrevocably agree
that in the event any payment shall be required to be made to any Secured Party
under this Guaranty Supplement, the Subsidiary Guaranty or any other guaranty,
the undersigned will contribute, to the maximum extent permitted by applicable
law, such amounts to each other Guarantor and each other guarantor so as to
maximize the aggregate amount paid to the Secured Parties under or in respect of
the Loan Documents.

            Section 2. Obligations Under the Guaranty. The undersigned hereby
agree, as of the date first above written, to be bound as a Guarantor by all of
the terms and conditions of the Subsidiary Guaranty to the same extent as each
of the other Guarantors thereunder. The undersigned further agree, as of the
date first above written, that each reference in the Subsidiary Guaranty to an
"ADDITIONAL GUARANTOR" or a "GUARANTOR" shall also mean and be a reference to
the undersigned, and each reference in any other Loan Document to a "SUBSIDIARY
GUARANTOR" or a "LOAN PARTY" shall also mean and be a reference to the
undersigned.

            Section 3. Representations and Warranties. The undersigned hereby
make each representation and warranty set forth in Section 6 of the Subsidiary
Guaranty to the same extent as each other Guarantor.

            Section 4. Delivery by Telecopier. Delivery of an executed
counterpart of a signature page to this Guaranty Supplement by telecopier shall
be effective as delivery of an original executed counterpart of this Guaranty
Supplement.

            Section 5. Governing Law; Jurisdiction; Waiver of Jury Trial, Etc.
(a) THIS GUARANTY SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE
WITH, THE LAWS OF THE STATE OF NEW YORK.

            (b) The undersigned hereby irrevocably and unconditionally submit,
each for itself and its property, to the nonexclusive jurisdiction of any New
York State court or any federal court of the United States of America sitting in
New York City, and any appellate court from any thereof, in any action or
proceeding arising out of or relating to this Guaranty Supplement, the
Subsidiary Guaranty or any of the other Loan Documents to which it is or is to
be a party, or for recognition or enforcement of any judgment, and the
undersigned hereby irrevocably and unconditionally agree that all claims in
respect of any such action or proceeding may be heard and determined in any such
New York State court or, to the extent permitted by law, in such federal court.
The undersigned agree that a final judgment in any such action or proceeding
shall be conclusive and may be enforced in other jurisdictions by suit on the

                                       2
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judgment or in any other manner provided by law. Nothing in this Guaranty
Supplement or the Subsidiary Guaranty or any other Loan Document shall affect
any right that any party may otherwise have to bring any action or proceeding
relating to this Guaranty Supplement, the Subsidiary Guaranty or any of the
other Loan Documents to which it is or is to be a party in the courts of any
other jurisdiction.

            (c) Each of the undersigned irrevocably and unconditionally waives,
to the fullest extent it may legally and effectively do so, any objection that
it may now or hereafter have to the laying of venue of any suit, action or
proceeding arising out of or relating to this Guaranty Supplement, the
Subsidiary Guaranty or any of the other Loan Documents to which it is or is to
be a party in any New York State or federal court. The undersigned hereby
irrevocably waive, to the fullest extent permitted by law, the defense of an
inconvenient forum to the maintenance of such suit, action or proceeding in any
such court.

            (d) THE UNDERSIGNED HEREBY IRREVOCABLY WAIVE ALL RIGHT TO TRIAL BY
JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM (WHETHER BASED ON CONTRACT, TORT
OR OTHERWISE) ARISING OUT OF OR RELATING TO ANY OF THE LOAN DOCUMENTS, THE
ADVANCES OR THE ACTIONS OF ANY SECURED PARTY IN THE NEGOTIATION, ADMINISTRATION,
PERFORMANCE OR ENFORCEMENT THEREOF.

                                               Very truly yours,

                                               FERROUS RESOURCES, LLC

                                               By:  /S/ MARK D. MILLETT
                                                   -----------------------------
                                                   Mark D. Millett, President

                                               STLD HOLDINGS, INC.

                                               By:  /S/ MARK D. MILLETT
                                                   -----------------------------
                                                   Mark D. Millett, President

                                       3<PAGE>
                                                                   EXHIBIT 10.2b

                         SUBSIDIARY GUARANTY SUPPLEMENT

                                                               September 6, 2002

JPMorgan Chase Bank, as Administrative Agent
270 Park Avenue
New York, New York 10017

Attention:  Deirdre Wall

               Credit Agreement dated as of March 26, 2002 among
Steel Dynamics, Inc, an Indiana corporation (the "BORROWER"), the Lender Parties
    party to the Credit Agreement, JPMorgan Chase Bank, as Collateral Agent,
        JPMorgan Chase Bank, as Administrative Agent, and Morgan Stanley
            Senior Funding, Inc., as Arranger and Syndication Agent

Ladies and Gentlemen:

            Reference is made to the above-captioned Credit Agreement and to the
Subsidiary Guaranty referred to therein (such Subsidiary Guaranty, as in effect
on the date hereof and as it may hereafter be amended, supplemented or otherwise
modified from time to time, together with this Guaranty Supplement, being the
"SUBSIDIARY GUARANTY"). The capitalized terms defined in the Subsidiary Guaranty
or in the Credit Agreement and not otherwise defined herein are used herein as
therein defined.

            Section 1. Guaranty; Limitation of Liability. (a) The undersigned
hereby absolutely, unconditionally and irrevocably guarantees the punctual
payment when due, whether at scheduled maturity or on any date of a required
prepayment or by acceleration, demand or otherwise, of all Obligations of each
other Loan Party now or hereafter existing under or in respect of the Loan
Documents (including, without limitation, any extensions, modifications,
substitutions, amendments or renewals of any or all of the foregoing
Obligations), whether direct or indirect, absolute or contingent, and whether
for principal, interest, premium, fees, indemnities, contract causes of action,
costs, expenses or otherwise (such Obligations being the "GUARANTEED
OBLIGATIONS"), and agrees to pay any and all expenses (including, without
limitation, fees and expenses of counsel) incurred by the Administrative Agent
or any other Secured Party in enforcing any rights under this Guaranty
Supplement, the Subsidiary Guaranty or any other Loan Document. Without limiting
the generality of the foregoing, the undersigned's liability shall extend to all
amounts that constitute part of the Guaranteed Obligations and would be owed by
any other Loan Party to any Secured Party under or in respect of the Loan
Documents but for the fact that they are unenforceable or not allowable due to
the existence of a bankruptcy, reorganization or similar proceeding involving
such other Loan Party.

            (b)   The undersigned, and by its acceptance of this Guaranty
Supplement, the Administrative Agent and each other Secured Party, hereby
confirms that it is the intention of all such Persons that this Guaranty
Supplement, the Subsidiary Guaranty and the Obligations of the undersigned
hereunder and thereunder not constitute a fraudulent transfer or conveyance for
<PAGE>
                                       2

purposes of Bankruptcy Law, the Uniform Fraudulent Conveyance Act, the Uniform
Fraudulent Transfer Act or any similar foreign, federal or state law to the
extent applicable to this Guaranty Supplement, the Subsidiary Guaranty and the
Obligations of the undersigned hereunder and thereunder. To effectuate the
foregoing intention, the Administrative Agent, the other Secured Parties and the
undersigned hereby irrevocably agree that the Obligations of the undersigned
under this Guaranty Supplement and the Subsidiary Guaranty at any time shall be
limited to the maximum amount as will result in the Obligations of the
undersigned under this Guaranty Supplement and the Subsidiary Guaranty not
constituting a fraudulent transfer or conveyance.

            (c)   The undersigned hereby unconditionally and irrevocably agrees
that in the event any payment shall be required to be made to any Secured Party
under this Guaranty Supplement, the Subsidiary Guaranty or any other guaranty,
the undersigned will contribute, to the maximum extent permitted by applicable
law, such amounts to each other Guarantor and each other guarantor so as to
maximize the aggregate amount paid to the Secured Parties under or in respect of
the Loan Documents.

            Section 2. Obligations Under the Guaranty. The undersigned hereby
agrees, as of the date first above written, to be bound as a Guarantor by all of
the terms and conditions of the Subsidiary Guaranty to the same extent as each
of the other Guarantors thereunder. The undersigned further agrees, as of the
date first above written, that each reference in the Subsidiary Guaranty to an
"ADDITIONAL GUARANTOR" or a "GUARANTOR" shall also mean and be a reference to
the undersigned, and each reference in any other Loan Document to a "SUBSIDIARY
GUARANTOR" or a "LOAN PARTY" shall also mean and be a reference to the
undersigned.

            Section 3. Representations and Warranties. The undersigned hereby
makes each representation and warranty set forth in Section 6 of the Subsidiary
Guaranty to the same extent as each other Guarantor.

            Section 4. Delivery by Telecopier. Delivery of an executed
counterpart of a signature page to this Guaranty Supplement by telecopier shall
be effective as delivery of an original executed counterpart of this Guaranty
Supplement.

            Section 5. Governing Law; Jurisdiction; Waiver of Jury Trial, Etc.
(A) THIS GUARANTY SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE
WITH, THE LAWS OF THE STATE OF NEW YORK.

            (b)   The undersigned hereby irrevocably and unconditionally
submits, for itself and its property, to the nonexclusive jurisdiction of any
New York State court or any federal court of the United States of America
sitting in New York City, and any appellate court from any thereof, in any
action or proceeding arising out of or relating to this Guaranty Supplement, the
Subsidiary Guaranty or any of the other Loan Documents to which it is or is to
be a party, or for recognition or enforcement of any judgment, and the
undersigned hereby irrevocably and unconditionally agrees that all claims in
respect of any such action or proceeding may be heard and determined in any such
New York State court or, to the extent permitted by law, in such federal court.
The undersigned hereby agrees that service of process in any such action or
proceeding brought in any such New York state court or in such federal court may
be made upon CT Corporation System at its offices at 111 Eighth Avenue, 13th
Floor, New York, New York
<PAGE>
                                       3

10011 (the "PROCESS AGENT") and the undersigned hereby irrevocably appoints the
Process Agent its authorized agent to accept such service of process, and agrees
that the failure of the Process Agent to give any notice of any such service
shall not impair or affect the validity of such service or of any judgment
rendered in any action or proceeding based thereon. The undersigned hereby
further irrevocably consents to the service of process in any action or
proceeding in such courts by the mailing thereof by any parties hereto by
registered or certified mail, postage prepaid, to the undersigned at its address
specified pursuant to Section 9 of the Subsidiary Guaranty. The undersigned
agrees that a final judgment in any such action or proceeding shall be
conclusive and may be enforced in other jurisdictions by suit on the judgment or
in any other manner provided by law. Nothing in this Guaranty Supplement or the
Subsidiary Guaranty or any other Loan Document shall affect any right that any
party may otherwise have to bring any action or proceeding relating to this
Guaranty Supplement, the Subsidiary Guaranty or any of the other Loan Documents
to which it is or is to be a party in the courts of any other jurisdiction.

            (c)   The undersigned irrevocably and unconditionally waives, to the
fullest extent it may legally and effectively do so, any objection that it may
now or hereafter have to the laying of venue of any suit, action or proceeding
arising out of or relating to this Guaranty Supplement, the Subsidiary Guaranty
or any of the other Loan Documents to which it is or is to be a party in any New
York State or federal court. The undersigned hereby irrevocably waives, to the
fullest extent permitted by law, the defense of an inconvenient forum to the
maintenance of such suit, action or proceeding in any such court.

            (d)   THE UNDERSIGNED HEREBY IRREVOCABLY WAIVES ALL RIGHT TO TRIAL
BY JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM (WHETHER BASED ON CONTRACT,
TORT OR OTHERWISE) ARISING OUT OF OR RELATING TO ANY OF THE LOAN DOCUMENTS, THE
ADVANCES OR THE ACTIONS OF ANY SECURED PARTY IN THE NEGOTIATION, ADMINISTRATION,
PERFORMANCE OR ENFORCEMENT THEREOF.

                                       Very truly yours,

                                       DYNAMIC BAR PRODUCTS, LLC

                                       By: Steel Dynamics, Inc., its sole member

                                       By /s/  Theresa E. Wagler
                                          Title: Assistant Treasurer

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