Sec Form 4 Filing - ALEXANDER PETER @ BMC STOCK HOLDINGS, INC. - 2017-12-31

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 ALEXANDER PETER 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 X __ Officer (give title below) _____ Other (specify below) See Remarks (Last) (First) (Middle) C/O BMC STOCK HOLDINGS, INC., 980 HAMMOND DR NE, SUITE 500 3. Date of Earliest Transaction (MM/DD/YY) 12/31/2017 (Street) ATLANTA, GA30328 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 116,035 ( 1 ) I See Footnote ( 2 ) Common Stock 292,349 ( 1 ) I See Footnote ( 3 ) Common Stock 12/31/2017 F 11,988 ( 4 ) D $ 25.3 88,703 D

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 ALEXANDER PETER C/O BMC STOCK HOLDINGS, INC. 980 HAMMOND DR NE, SUITE 500 ATLANTA, GA30328 X See Remarks Signatures /s/ Lanesha Minnix by Power of Attorney for Peter C. Alexander 01/03/2018 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Beneficial ownership of Kinderoaks Family LLC ("Kinderoaks") includes, and beneficial ownership of the Peter C. Alexander Revocable Trust dated August 8, 2014 (the "Alexander Trust") excludes, 44,940 shares of common stock of the Issuer ("Common Stock") previously reported as beneficially owned by the Alexander Trust. These shares have historically been beneficially owned by Kinderoaks, but have been inadvertently included in the Alexander Trust's beneficial ownership. This change does not affect the Reporting Person's aggregate beneficial ownership of Common Stock. ( 2 )Kinderoaks is the beneficial owner of 116,035 shares of Common Stock. Mr. Alexander, who is a Manager of Kinderoaks, has shared voting and dispositive power of such reported securities. The Reporting Person expressly disclaims beneficial ownership of such securities, except to the extent of the Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed to be an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the Reporting Person is the beneficial owner of such securities. ( 3 )The Alexander Trust is the beneficial owner of 292,349 shares of Common Stock. Mr. Alexander, who is a trustee of the Alexander Trust, has shared voting and dispositive power over such reported securities. The Reporting Person expressly disclaims beneficial ownership of such securities, except to the extent of the Reporting Person's pecuniary interest therein. The filing of this statement shall not be deemed to be an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the Reporting Person is the beneficial owner of such securities. ( 4 )Reflects shares withheld to pay tax withholding requirements on vesting of previously granted restricted stock units. Effective March 30, 2016, the reporting person was granted 75,000 restricted stock units, vesting in equal one-third increments on December 31, 2016, December 31, 2017 and December 31, 2018, subject to the reporting person's continued employment with the issuer.

Remarks: President and Chief Executive Officer; Exhibit 24: Power of Attorney

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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