Statement of Changes in Beneficial Ownership (4)

FORM 4

[X] 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 OF SECURITIES

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3235-0287

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

1. Name and Address of Reporting Person * ALEXANDER MARK A	2. Issuer Name and Ticker or Trading Symbol BMC STOCK HOLDINGS, INC. [ BMCH ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director                    _____ 10% Owner _____ Officer (give title below)    _____ Other (specify below)
(Last)          (First)          (Middle) C/O BMC STOCK HOLDINGS, INC., 4800 FALLS OF NEUSE RD, SUITE 400	3. Date of Earliest Transaction (MM/DD/YYYY) 1/1/2021
(Street) RALEIGH, NC 27609 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	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 Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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	1/1/2021		D		19587 (1)	D	(1)	0	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		7. Title and Amount of Securities Underlying Derivative Security (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

Explanation of Responses:

(1)

Represents a disposition in connection with the Agreement and Plan of Merger, dated as of August 26, 2020 (the "Merger Agreement"), by and among Builders FirstSource, Inc. ("BFS"), Boston Merger Sub I Inc. ("Merger Sub"), and BMC Stock Holdings, Inc. ("BMC"), pursuant to which Merger Sub merged with and into BMC, with BMC surviving as a wholly owned subsidiary of BFS. At the effective time of such merger, each outstanding BMC restricted stock unit vested and settled into 1.3125 shares of BFS common stock in accordance with the Merger Agreement and each share of BMC common stock was converted into the right to receive 1.3125 shares of BFS common stock in accordance with the Merger Agreement.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
ALEXANDER MARK A C/O BMC STOCK HOLDINGS, INC. 4800 FALLS OF NEUSE RD, SUITE 400 RALEIGH, NC 27609	X

Signatures
/s/ Timothy D. Johnson by power of attorney for Mark A. Alexander		1/5/2021
**Signature of Reporting Person		Date