Sec Form 4 Filing - Grupo Argos S.A. @ Summit Materials, Inc. - 2025-02-10

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 Grupo Argos S.A. 2. Issuer Name and Ticker or Trading Symbol Summit Materials, Inc. [ SUM] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) CARRERA 43A # 1A SUR - 143,, EDIFICIO SANTILLANA, TORRE SUR, PISO 3 3. Date of Earliest Transaction (MM/DD/YY) 02/10/2025 (Street) MEDELLIN, F8050021 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 Class A Common Stock ( 1 ) ( 2 ) 02/10/2025 D( 3 )( 4 ) 48,547,584 ( 3 ) ( 4 ) ( 5 ) D $ 52.5 ( 3 ) ( 4 ) 0 I Held by Argos SEM, LLC Class A Common Stock ( 1 ) ( 2 ) 02/10/2025 D( 3 )( 4 ) 6,172,416 ( 3 ) ( 4 ) ( 6 ) D $ 52.5 ( 3 ) ( 4 ) 0 I Held by Valle Cement Investments, Inc. Series A Non-Convertible Preferred Stock ( 1 ) ( 2 ) 02/10/2025 D( 3 )( 4 ) 1 ( 3 ) ( 4 ) ( 7 ) D $ 0 ( 3 ) ( 4 ) 0 I Held by Cementos Argos S.A.

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

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Grupo Argos S.A. CARRERA 43A # 1A SUR - 143, EDIFICIO SANTILLANA, TORRE SUR, PISO 3 MEDELLIN, F8050021 X X Cementos Argos S.A. CARRERA 43A # 1A SUR - 143, EDIFICIO SANTILLANA, TORRE SUR, PISO 3 MEDELLIN, F8050021 X X Argos SEM, LLC 251 LITTLE FALLS DRIVE WILMINGTON, DE19808 X X Valle Cement Investments, Inc. CAPITAL PLAZA BUILDING, 15TH FLOOR, PASEO ROBERTO MOTTA, COSTA DEL ESTE PANAMA, R10816-02984 X X Signatures /s/ Grupo Argos S.A., By: Rafael Olivella, Title: Vice President 02/10/2025 Signature of Reporting Person Date /s/ Valle Cement Investments, Inc., By: Gari Manuel de la Rosa, Title: President 02/10/2025 Signature of Reporting Person Date /s/ Argos SEM, LLC, By: Gustavo Adolfo Uribe, Title: President 02/10/2025 Signature of Reporting Person Date /s/ Cementos Argos S.A., By: Maria Isabel Echeverri, Title: Vice President 02/10/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )This Form 4 is filed jointly by (i) Grupo Argos S.A., a sociedad anonima incorporated in the Republic of Colombia ("Grupo Argos"), (ii) Argos SEM, LLC, a Delaware limited liability company ("Argos SEM"), (iii) Valle Cement Investments, Inc., a sociedad anonima incorporated in the Republic of Panama ) ("Valle Cement") and (iv) Cementos Argos S.A., a sociedad anonima incorporated in the Republic of Colombia ("Cementos Argos" and collectively with Grupo Argos, Argos SEM and Valle Cement, the "Reporting Persons"). Grupo Argos is the controlling shareholder of Cementos Argos and has the power to control and direct Cementos Argos. Cementos Argos is the sole shareholder of Argos SEM and Valle Cement. By reason of these relationships and the provisions of Rule 13d-3 of the Securities Exchange Act of 1934, as amended, each of the Reporting Persons may be deemed to beneficially own the shares of Common Stock of the Issuer directly owned by Valle Cement, Argos SEM and Cementos Argos. ( 2 )(Continued from footnote 1) Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein except to the extent of its pecuniary interest therein. ( 3 )Reflects the disposition of shares of common stock, par value $0.01 per share ("Common Stock"), of Summit Materials Inc. ("Issuer"), in connection with the consummation of the transactions contemplated by the Agreement and Plan of Merger, dated as of November 24, 2024 (the "Merger Agreement"), by and among the Issuer, Quikrete Holdings, Inc. ("Parent") and Soar Subsidiary, Inc. ("Merger Sub"), a wholly owned subsidiary of Parent, pursuant to which, at the effective time of the Merger (the "Effective Time"), Merger Sub merged with and into the Issuer, with the Issuer surviving as a subsidiary of Parent (the "Merger"). Pursuant to the Merger, on the Effective Time, each issued and outstanding share of the Issuer's (i) Class A Common Stock and (ii) Class B common stock, par value $0.01 per share (together with the Class A Common Stock described in the foregoing clause (i), "Company Common Shares" ( 4 )(Continued from footnote 3) and each, a "Company Common Share") (other than any Company Common Shares that are held by the Issuer as treasury stock or held by Purchaser, Merger Sub or any other subsidiary of Purchaser or the Issuer or any Company Common Shares as to which appraisal rights have been properly exercised in accordance with Delaware law), was automatically canceled and retired and converted into the right to receive $52.50 per share in cash, without interest and subject to deduction for any required withholding (the "Merger Consideration"). Furthermore, on the Effective Time of the Merger, all shares of preferred stock of the Issuer, par value $0.01 per share, outstanding immediately prior to the Effective Time, ceased to exist as they were automatically canceled and retired for no consideration. ( 5 )Represents securities of the Issuer, directly owned by Argos SEM, which is a wholly-owned subsidiary of Cementos Argos, which is a majority-owned subsidiary of Grupo Argos. Grupo Argos, as the controlling shareholder of Cementos Argos, which in turn is the sole shareholder of Argos SEM, has the power to vote and to dispose of the Company Common Shares directly owned by Argos SEM. As a result of this relationship, Grupo Argos may be deemed to be an indirect beneficial owner of the securities that are beneficially owned by Argos SEM. By reason of the provisions of Rule 13d-3 of the Securities Exchange Act of 1934, as amended, each of the Reporting Persons may be deemed to beneficially own the Company Common Shares directly owned by Argos SEM. ( 6 )Represents securities of the Issuer, directly owned by Valle Cement, which is a wholly-owned subsidiary of Cementos Argos, which is a majority-owned subsidiary of Grupo Argos. Grupo Argos, as the controlling shareholder of Cementos Argos, which in turn is the sole shareholder of Valle Cement, has the power to vote and to dispose of the Company Common Shares directly owned by Valle Cement. As a result of this relationship, Grupo Argos may be deemed to be an indirect beneficial owner of the securities that are beneficially owned by Valle Cement. By reason of the provisions of Rule 13d-3 of the Securities Exchange Act of 1934, as amended, each of the Reporting Persons may be deemed to beneficially own the Company Common Shares directly owned by Valle Cement. ( 7 )Represents securities of the Issuer, directly owned by Cementos Argos, which is a majority-owned subsidiary of Grupo Argos. Grupo Argos, as the controlling shareholder of Cementos Argos, has the power to vote and to dispose of the share of Series A Non-Convertible Preferred Stock of the Issuer directly owned by Cementos Argos. As a result of this relationship, Grupo Argos may be deemed to be an indirect beneficial owner of the securities that are beneficially owned by Cementos Argos. By reason of the provisions of Rule 13d-3 of the Securities Exchange Act of 1934, as amended, each of the Reporting Persons may be deemed to beneficially own the shares of Common Stock of the Issuer directly owned by Cementos Argos.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* 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).

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