Summit Materials (SUM) Form 3 Summit Materials / Deon MacMillan ownership change

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person^*

MacMillan Deon

(Last) (First) (Middle)

C/O SUMMIT MATERIALS, INC.

1550 WYNKOOP STREET, 3RD F LOOR

(Street)

DENVER CO 80202

(City) (State) (Zip)

2. Date of Event Requiring Statement (Month/Day/Year)
03/29/2021

3. Issuer Name and Ticker or Trading Symbol
Summit Materials, Inc. [ SUM ]

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
See Remarks

5. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Class A Common Stock	3,711	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Units	(1)	(1)	Class A Common Stock	11,215	(2)	D

Explanation of Responses:

1. Each restricted stock unit represents a contingent right to receive one share of Class A common stock of the Issuer ("Class A Common Stock"). The restricted stock units will be settled in either Class A Common Stock or cash (or a combination thereof) at the discretion of the Issuer's compensation committee.

2. These restricted stock units vest as follows: (a) 58.33% vest on March 9, 2022, and (b) the remaining vest on March 9, 2023.

Remarks:

Title: EVP, Chief People Officer and Head of Corporate Communications Exhibit 24 - Power of Attorney

	/s/ Christopher B. Gaskill, as Attorney-in-Fact	04/01/2021
	** Signature of Reporting Person	Date
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 5 (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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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