Sec Form 4 Filing - WHITEBOX ADVISORS LLC @ A. M. Castle & Co. - 2020-03-27

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 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 WHITEBOX ADVISORS LLC 2. Issuer Name and Ticker or Trading Symbol A. M. Castle & Co. [ CTAM] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 3033 EXCELSIOR BOULEVARD, SUITE 500 3. Date of Earliest Transaction (MM/DD/YY) 03/27/2020 (Street) MINNEAPOLIS, MN55416 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 03/27/2020 J( 2 ) 20,945,875 A $ 0 21,346,747 I See Footnote ( 5 ) ( 7 ) Common Stock 03/27/2020 J( 2 ) 20,229,264 A $ 0 20,610,221 I See Footnote ( 6 ) ( 7 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 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 5.0% / 7.0% Convertible Sr Secured PIK Toggle Notes due 2022 ( 1 ) ( 3 ) 03/27/2020 J( 2 ) ( 3 ) ( 3 ) Common Stock ( 2 ) ( 2 ) 0 I See Footnote ( 5 ) ( 7 ) 5.0% / 7.0% Convertible Sr Secured PIK Toggle Notes due 2022 ( 1 ) ( 3 ) 03/27/2020 J( 2 ) ( 3 ) ( 3 ) Common Stock ( 2 ) ( 2 ) 0 I See Footnote ( 6 ) ( 7 ) 3.00% / 5.00% Convertible Senior Secured Notes due 2024 ( 1 ) ( 3 ) 03/27/2020 J( 2 ) ( 3 ) ( 3 ) Common Stock ( 4 ) 62,223,614 ( 2 ) $ 28,361,286 I See Footnote ( 5 ) ( 7 ) 3.00% / 5.00% Convertible Senior Secured Notes due 2024 ( 1 ) ( 3 ) 03/27/2020 J( 2 ) ( 3 ) ( 3 ) Common Stock ( 4 ) 60,094,788 ( 2 ) $ 27,390,975 I See Footnote ( 6 ) ( 7 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other WHITEBOX ADVISORS LLC 3033 EXCELSIOR BOULEVARD, SUITE 500 MINNEAPOLIS, MN55416 X WHITEBOX GENERAL PARTNER LLC 3033 EXCELSIOR BOUELVARD, SUITE 500 MINNEAPOLIS, MN55416 X Signatures Whitebox Advisors LLC By: /s/ Daniel Altabef, Title: General Counsel Regulatory Affairs & Compliance 03/31/2020 Signature of Reporting Person Date Whitebox General Partner LLC By: /s/ Daniel Altabef, Title: General Counsel Regulatory Affairs & Compliance 03/31/2020 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The Reporting Persons do not acknowledge that the Issuer's 5.0% / 7.0% Convertible Sr Secured PIK Toggle Notes due 2022 (the "Old Notes") and 3.00% / 5.00% Convertible Senior Secured PIK Toggle Notes due 2024 (the "New Notes") are derivative securities for purposes of Section 16 of the Exchange Act, as amended (the "Exchange Act"). ( 2 )On March 27, 2020, the Issuer completed an exchange transaction (the "Exchange"), whereby it issued the New Notes and shares of its Common Stock in exchange for its existing Old Notes. In connection with the Exchange, the Reporting Persons received an aggregate of 20,945,875 shares of Common Stock and $28,361,286 in aggregate principal amount of New Notes in exchange for $56,701,867 in aggregate principal amount of Old Notes beneficially owned by the Reporting Persons, plus accrued and unpaid interest thereon. ( 3 )The New Notes are convertible at the election of the holder at any time prior to the close of business on the trading day immediately preceding August 31, 2024, the maturity date of the New Notes. The New Notes are convertible into shares of Common Stock at an initial conversion rate of 2.1939631 shares of Common Stock per $1.00 principal amount of New Notes (subject to adjustment in certain circumstances). ( 4 )Upon conversion of the New Notes, the settlement of the conversion right may, at the option of the Issuer, be in the form of shares of Common Stock, cash or a combination of cash and shares of Common Stock. ( 5 )These securities are directly owned by certain private funds managed by Whitebox Advisors LLC and may be deemed to be beneficially owned by Whitebox Advisors LLC by virtue of its role as the investment manager of such private funds. ( 6 )These securities are directly owned by certain private funds in which Whitebox General Partner LLC serves as their general partner and may be deemed to be beneficially owned by Whitebox General Partner LLC by virtue of its role as the general partner of such private funds. ( 7 )The Reporting Persons disclaim beneficial ownership of the reported securities except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that such Reporting Person is the beneficial owner of the securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

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* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

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