Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Class A Common Stock^{F1,F3,F8,F9,F10,F11,F12}	Nov 16, 2016	C	13,349,610	—	A	13,349,610	I	See Footnotes
Class A Common Stock^{F2,F3,F8,F9,F10,F11,F12}	Nov 16, 2016	S	13,349,610	$21.87	D	0	I	See Footnotes
Class A Common Stock^{F1,F4,F8,F9,F10,F11,F12}	Nov 16, 2016	C	2,814,207	—	A	2,814,207	I	See Footnotes
Class A Common Stock^{F2,F4,F8,F9,F10,F11,F12}	Nov 16, 2016	S	2,814,207	$21.87	D	0	I	See Footnotes
Class A Common Stock^{F1,F5,F8,F9,F10,F11,F12}	Nov 16, 2016	C	253,891	—	A	253,891	I	See Footnotes
Class A Common Stock^{F2,F5,F8,F9,F10,F11,F12}	Nov 16, 2016	S	253,891	$21.87	D	0	I	See Footnotes
Class A Common Stock^{F1,F6,F8,F9,F10,F11,F12}	Nov 16, 2016	C	21,513	—	A	21,513	I	See Footnotes
Class A Common Stock^{F2,F6,F8,F9,F10,F11,F12}	Nov 16, 2016	S	21,513	$21.87	D	0	I	See Footnotes
Class A Common Stock^{F1,F7,F8,F9,F10,F11,F12}	Nov 16, 2016	C	12,501	—	A	12,501	I	See Footnotes
Class A Common Stock^{F2,F7,F8,F9,F10,F11,F12}	Nov 16, 2016	S	12,501	$21.87	D	0	I	See Footnotes

Table II — derivative securities

Security	Conv. / exercise price	Date	Code	Shares	A/D	Exercisable	Expires	Underlying	Underlying shares	D/I
LP Units of Summit Materials Holdings L.P.^{F1,F3,F8,F9,F10,F11,F12}	—	Nov 16, 2016	C	13,349,610	D	—	—	Class A Common Stock	13,349,610	I
LP Units of Summit Materials Holdings L.P.^{F1,F4,F8,F9,F10,F11,F12}	—	Nov 16, 2016	C	2,814,207	D	—	—	Class A Common Stock	2,814,207	I
LP Units of Summit Materials Holdings L.P.^{F1,F5,F8,F9,F10,F11,F12}	—	Nov 16, 2016	C	253,891	D	—	—	Class A Common Stock	253,891	I
LP Units of Summit Materials Holdings L.P.^{F1,F6,F8,F9,F10,F11,F12}	—	Nov 16, 2016	C	21,513	D	—	—	Class A Common Stock	21,513	I
LP Units of Summit Materials Holdings L.P.^{F1,F7,F8,F9,F10,F11,F12}	—	Nov 16, 2016	C	12,501	D	—	—	Class A Common Stock	12,501	I

Explanation of responses

F1Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, limited partnership units of Summit Materials Holdings L.P. ("LP Units") held by the Reporting Persons are exchangeable for shares of the issuer's Class A common stock ("Common Stock") on a one-for-one basis.
F10Due to the limitations of the electronic filing system Blackstone Holdings II L.P., Blackstone Holdings I/II GP Inc., The Blackstone Group L.P., Blackstone Group Management L.L.C. and Stephen A. Schwarzman are filing a separate Form 4.
F11Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person has responsibility for the accuracy or completeness of information supplied by another Reporting Person.
F12Each of the Reporting Persons (other than the Blackstone Funds to the extent they directly hold securities reported herein), disclaims beneficial ownership of the securities held by the Blackstone Funds, except to the extent of such Reporting Person's pecuniary interest therein, if any, and, pursuant to Rule 16a-1(a)(4) under the Securities Exchange Act of 1934, each of the Reporting Persons (other than the Blackstone Funds to the extent they directly hold securities reported herein) states that the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of all of the reported securities for purposes of Section 16 or for any other purpose.
F2This amount represents the $22.10 public offering price per share of Common Stock, less the underwriting discount of $0.23 per share of Common Stock.
F3Reflects securities of the issuer held directly by Blackstone Capital Partners (Delaware) V-NQ L.P.
F4Reflects securities of the issuer held directly by Blackstone Capital Partners (Delaware) NQ V-AC L.P.
F5Reflects securities of the issuer held directly by Summit BCP Intermediate Holdings L.P. The general partner of Summit BCP Intermediate Holdings L.P. is Summit BCP Intermediate Holdings GP, Ltd. Summit BCP Intermediate Holdings GP, Ltd. is owned by Blackstone Capital Partners (Delaware) V-NQ L.P., Blackstone Capital Partners (Delaware) NQ V-AC L.P., Blackstone Family Investment Partnership (Delaware) V-NQ L.P. and Blackstone Participation Partnership (Delaware) V-NQ L.P.
F6Reflects securities of the issuer held directly by Blackstone Family Investment Partnership (Delaware) V-NQ L.P.
F7Reflects securities of the issuer held directly by Blackstone Participation Partnership (Delaware) V-NQ L.P. (collectively with Blackstone Capital Partners (Delaware) V-NQ L.P., Blackstone Capital Partners (Delaware) NQ V-AC L.P., Summit BCP Intermediate Holdings L.P. and Blackstone Family Investment Partnership (Delaware) V-NQ L.P., the "Blackstone Funds").
F8The general partner of each of Blackstone Capital Partners (Delaware) V-NQ L.P. and Blackstone Capital Partners (Delaware) NQ V-AC L.P. is Blackstone Management Associates (Cayman) V-NQ L.P. The general partners of each of Blackstone Management Associates (Cayman) V-NQ L.P., Blackstone Family Investment Partnership (Delaware) V-NQ L.P. and Blackstone Participation Partnership (Delaware) V-NQ L.P. are Blackstone LR Associates (Cayman) V-NQ Ltd. and BCP V-NQ GP L.L.C.
F9Blackstone Holdings II L.P. is the sole member of BCP V-NQ GP L.L.C. and the controlling shareholder of Blackstone LR Associates (Cayman) V-NQ Ltd. The general partner of Blackstone Holdings II L.P. is Blackstone Holdings I/II GP Inc. The sole shareholder of Blackstone Holdings I/II GP Inc. is The Blackstone Group L.P. The general partner of The Blackstone Group L.P. is Blackstone Group Management L.L.C. Blackstone Group Management L.L.C. is wholly owned by Blackstone's senior managing directors and controlled by its founder, Stephen A. Schwarzman.