Exhibit 10.1

FORM OF FIRST AMENDMENT TO AMENDED AND RESTATED

TRANSACTION SUPPORT AGREEMENT

THIS FIRST AMENDMENT TO AMENDED AND RESTATED TRANSACTION SUPPORT AGREEMENT (this
“Amendment”) is made as of May     , 2016 by and among (a) the undersigned
Support Party and (b) the A.M. Castle & Co. (the “Company”) (together, the
“Parties”) and amends that certain Amended and Restated Transaction Support
Agreement, dated as of March 16, 2016, by and among the Parties (the “TSA”).
Capitalized terms used but not otherwise defined herein have the meanings
ascribed to such terms in the TSA.

WHEREAS, in order to accelerate the consummation of the exchanges anticipated
under the TSAs ,permit the direct exchange of some or all of the Existing
Convertible Notes (as defined in the TSA) into Company Common Stock (as defined
in the TSA) and make certain technical changes to the definition of the
Make-Whole Premium (as defined in the Term Sheet attached to the TSA), the
Parties desire to amend the TSA as set forth in this Amendment;

WHEREAS, in order to fully implement certain terms of the amendment to the
various Transaction Support Agreements, dated January 26, 2016, the Parties
desire to make a conforming change that was inadvertently not made to the
portion of the Term Sheet relating to the New Convertible Notes; and

WHEREAS, Section 9 of the TSA permits the Company and the Required Supporting
Stakeholders to amend the TSA in the manner set forth herein;

NOW, THEREFORE, in consideration of the mutual covenants and agreements and
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the Parties hereby agree as follows:

 

1. Amendments to the TSA.

 

  a. The paragraph under the caption “Convertible Note Exchanges—Exchange Offer
Overview” in the Term Sheet is amended and restated as follows:

In each of the Convertible Note Exchanges, the Company will, in exchange for the
Company’s existing 7.00% Convertible Senior Notes due 2017 (the “Existing
Convertible Notes”) that are held by each Supporting Convertible Noteholder,
offer to issue to such Supporting Convertible Noteholder (each, an “Exchanging
Convertible Noteholder”) either:

 

  (i) new 5.25% Senior Secured Convertible Notes due 2019 (the “New Convertible
Notes”) on the terms and conditions set forth in this Term Sheet (the “New
Convertible Notes Option”); or

 

  (ii) shares of Company Common Stock on the terms and conditions set forth in
this Term Sheet (the “Common Stock Option”); or

 

  (iii) in the sole discretion of the Supporting Convertible Noteholder (as
defined in the TSA), a combination of (i) and (ii).

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If an Exchanging Convertible Noteholder elects the Common Stock Option, in whole
or in part, with respect to Existing Convertible Notes, the issuance of the
Company Common Stock to such Exchanging Convertible Noteholder in exchange for
Existing Convertible Notes shall take place on May     , 2016, and such date
shall be the “Convertible Note Exchange Settlement Date” with respect to such
Existing Convertible Notes.

If an Exchanging Convertible Noteholder elects the New Convertible Notes Option,
in whole or in part, with respect to Existing Convertible Notes, the issuance of
New Convertible Notes shall occur on May     , 2016, and such date shall be the
“Convertible Note Exchange Settlement Date” with respect to such Existing
Convertible Notes.

The exchange(s) pursuant to the New Convertible Notes Option and the Common
Stock Option shall be consummated pursuant to separate exchange agreements,
which shall more particularly describe the mechanics of such exchange(s).

For the avoidance of doubt, regardless of whether any Convertible Note Exchange
Settlement Date precedes the date that the Conversion Shares Registration
Statement (as defined below) is declared effective by the SEC, the Company shall
continue to use its commercially reasonable efforts to have such registration
statement declared effective by the SEC as soon as practicable.

 

  b. The paragraph under the caption “Convertible Note Exchanges—Exchange
Consideration” on the Term Sheet is amended and restated as follows:

New Convertible Notes Option: For each $1,000 principal amount of Existing
Convertible Notes exchanged pursuant to the New Convertible Notes Option, on the
Convertible Note Exchange Settlement Date with respect thereto, the Company
shall issue to the Exchanging Convertible Noteholder $700 principal amount of
New Convertible Notes. The aggregate principal amount of New Convertible Notes
to be issued to each Exchanging Convertible Noteholder shall be an integral
multiple of $1,000, provided that on such Convertible Note Exchange Settlement
Date, the Company shall pay the Exchanging Convertible Noteholder cash in lieu
of

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any principal amount of New Convertible Notes in excess of such integral
multiple of $1,000 to which such Exchanging Convertible Noteholder would have
been entitled.

Common Stock Option: For each $1,000 principal amount of Existing Convertible
Notes exchanged pursuant to the Common Stock Option, the Company shall issue an
Exchanging Convertible Noteholder the number of shares of Company Common Stock
equal to:

 

  (A) $700 divided by $2.25 plus

 

  (B) (1) the Make-Whole Premium (as defined below, calculated based on a $700
principal amount of New Convertible Notes and an assumed first interest payment
date of June 30, 2016), divided by

(2) the greater of (x) 130% times $2.25 and (y) the average of the Daily VWAPs
(as defined in the indenture governing the Existing Convertible Notes) for the
20 VWAP Trading Days (as defined in the indenture governing the Existing
Convertible Notes) immediately preceding the Convertible Note Exchange
Settlement Date.

On the Convertible Note Exchange Settlement Date with respect to such exchanged
Existing Convertible Notes, the Company shall pay to the Exchanging Convertible
Noteholder cash in lieu of any fractional shares of Company Common Stock.

Accrued and Unpaid Interest: With respect to all Existing Convertible Notes
exchanged pursuant to either the New Convertible Notes Option or the Common
Stock Option, the Company shall pay in cash, on the relevant Convertible Note
Exchange Settlement Date, any accrued and unpaid interest owed to the Exchanging
Convertible Noteholder on account of its Existing Convertible Notes exchanged on
such Convertible Note Exchange Settlement Date.

 

  c. The paragraph under the caption “Convertible Note Exchanges—Summary of
Certain Material Terms of New Convertible Notes—Make-Whole Premium” on the Term
Sheet is amended and restated as follows:

Make-Whole Premium: “Make-Whole Premium” means, with respect to each $1,000 in
principal amount of New Convertible Notes, an amount equal to the present values
of all scheduled payments of interest on the New Convertible Notes to be
redeemed from the relevant redemption date (or conversion date, in the case

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of a conversion) to (and including) the earlier of (x) the fourth interest
payment date after such redemption date (or conversion date, as the case may be)
and (y) December 31, 2019 (excluding the Accrued Interest Amount), computed
using a discount rate equal to the yield on the U.S. treasury security whose
tenor most nearly approximates the time until each such interest payment plus
0.50%. It is understood for purposes of this definition that if a redemption
date or conversion date occurs other than on an interest payment date, (i) any
accrued and unpaid interest on the New Convertible Notes that is paid in cash on
the redemption date or conversion date shall be subtracted from the amount of
the first interest payment to be included in the calculation of the Make-Whole
Premium, and (ii) if there are fewer than 90 days left in the current interest
period as of such redemption date or conversion date, clause (x) should refer to
the fifth interest payment date after such redemption date or conversion date
rather than the fourth.

 

  d. Conforming Change to Term Sheet. Pursuant to an amendment to the
Transaction Support Agreement, dated January 26, 2016, the Parties agreed, among
other things, that the Company shall not repay, redeem, prepay, retire, defease
or otherwise satisfy the Existing Secured Notes using, directly or indirectly,
more than $10.0 million of borrowings under the Company’s ABL Facility (or any
indebtedness that is secured by a lien that ranks higher in priority than the
liens securing the New Secured Notes or the New Convertible Notes and the
guarantees thereof). This covenant was added under the section of the Term Sheet
captioned “Secured Note Exchange Offer—Summary of Certain Material Terms of New
Secured Notes—Additional Covenant.” A conforming change was inadvertently not
made to the portion of the Term Sheet relating to the New Convertible Notes. For
clarification purposes, the Parties hereby acknowledge and agree to this
conforming change and the paragraph under the caption “Convertible Note
Exchanges—Summary of Certain Material Terms of New Convertible Notes—Certain
Limitations on Refinancing of Certain Existing Debt” in the Term Sheet shall be
amended and restated in its entirety to read as follows (with underlining
showing text that has been added, for the convenience of the reader, but not
being incorporated into the Term Sheet):

The Company shall not refinance the Existing Convertible Notes or the Existing
Secured Notes with any indebtedness (i) that is senior (either in right of
payment or as to security) to the New Convertible Notes, (ii) as to which a
Person other than the Company or a guarantor of the New Convertible Notes is an
obligor or provides credit support or (iii) that has any scheduled amortization
payments or a maturity date that is earlier than 91 days after the maturity date
of the New Convertible Notes; except that such limitation shall not apply to
borrowings by the Company in an amount not to exceed $10.0 million under the
Senior Credit Facility, the proceeds of which are used to repay, redeem, prepay,
retire, defease or otherwise satisfy the Existing Secured Notes. Notwithstanding
the foregoing, the Company shall be permitted to

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subsequently issue additional New Secured Notes in exchange for Existing Secured
Notes on terms no more advantageous to the holders of such Existing Secured
Notes than the terms of the Secured Note Exchange were to the Supporting Secured
Noteholders, provided that such terms shall not include a Consent Solicitation
or the payment of any tender or consent fees.

 

  e. The second paragraph under the caption “Convertible Note
Exchanges—Registration Rights” in the Term Sheet is amended and restated as
follows:

The Company shall pay the holders of registrable securities under the Conversion
Shares Registration Rights Agreement a fee in cash equal to 5.00% of the
aggregate principal amount of such holders’ New Convertible Notes if it fails to
have the Conversion Shares Registration Statement declared effective at or prior
to June 30, 2016 and an additional fee of 0.50% of the aggregate principal
amount of such holders’ New Convertible Notes for each period of 30 days
thereafter that the Conversion Shares Registration Statement has not been
declared effective. Any such fees will be distributed pro rata among the
Supporting Convertible Noteholders based on the principal amount of New
Convertible Notes each Supporting Convertible Noteholder is entitled to based on
the number of Existing Convertible Notes held, assuming the Supporting
Convertible Noteholder elects the New Convertible Notes Option.

 

2. Ratification. Except as specifically provided for in this Amendment, no
changes, amendments, or other modifications have been made on or prior to the
date hereof or are being made to the terms of the TSA or the rights and
obligations of the Parties thereunder, all of which such terms are hereby
ratified and confirmed and remain in full force and effect.

 

3. Effect of Amendment. This Amendment shall be effective on the date on which
the Company shall have received signature pages from the Company and the
Required Supporting Stakeholders (the “Amendment Effective Date”). Following the
Amendment Effective Date, whenever the TSA is referred to in any agreements,
documents, and instruments, such reference shall be deemed to be to the TSA as
amended hereby.

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IN WITNESS WHEREOF, the Parties hereto have caused this Amendment to be executed
and delivered by their respective duly authorized officers, solely in their
respective capacity as officers of the undersigned and not in any other
capacity, as of the date first set forth above.

 

A.M. CASTLE & CO. By:  

 

Name:  

 

Title:  

 

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Dated:                     

SUPPORT PARTY SIGNATURE PAGE

 

Name of Institution:  

 

By:  

 

Name:  

 

Title:  

 

Telephone:  

 

Facsimile:  

 

OUTSTANDING PRINCIPAL AMOUNT OF EXISTING CONVERTIBLE NOTE CLAIMS

$        

OUTSTANDING PRINCIPAL AMOUNT OF NEW SENIOR NOTE CLAIMS

$