UNITED STATES 			SECURITIES AND EXCHANGE COMMISSION 				Washington, D.C. 20549 				SCHEDULE 13G 			Under the Securities Exchange Act of 1934 		GLOBAL BRASS AND COPPER HOLDINGS, INC. ---------------------------------------------------------------------------- 	 	 (Name of Issuer) common stock ---------------------------------------------------------------------------- 		 (Title of Class of Securities) 		 37953G103 ---------------------------------------------------------------------------- 	 (CUSIP Number) 	February 20, 2018 ---------------------------------------------------------------------------- 	(Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: [X] Rule 13d-1(b) [_] Rule 13d-1(c) [_] Rule 13d-1(d) *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes). ============================================================================= ----------------------------------------------------------------------------- CUSIP NO. 37953G103			13G			Page 2 of 8 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS. I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (entities only). Renaissance Technologies LLC 	26-0385758 ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS): (a) [_] (b) [_] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- 						(5) SOLE VOTING POWER NUMBER OF SHARES				 1,273,400 BENEFICIALLY OWNED				_____________________________ BY EACH REPORTING PERSON WITH:				(6) SHARED VOTING POWER 						 0 						_____________________________ 				(7) SOLE DISPOSITIVE POWER 						 1,273,400 					_____________________________ 						(8) SHARED DISPOSITIVE POWER 						 23,379 						______________________________ (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 			 1,296,779 ------------------------------------------------------------------------------ (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) [_] ------------------------------------------------------------------------------ (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 			 5.84 % ------------------------------------------------------------------------------ (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) 		 IA 				Page 2 of 8 pages ============================================================================= 				Page 3 of 8 pages ----------------------------------------------------------------------------- CUSIP NO. 37953G103			13G			Page 3 of 8 Pages ----------------------------------------------------------------------------- (1) NAMES OF REPORTING PERSONS. I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY). RENAISSANCE TECHNOLOGIES HOLDINGS CORPORATION 13-3127734 ----------------------------------------------------------------------------- (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a) [_] (b) [_] ----------------------------------------------------------------------------- (3) SEC USE ONLY ----------------------------------------------------------------------------- (4) CITIZENSHIP OR PLACE OF ORGANIZATION Delaware ----------------------------------------------------------------------------- 						(5) SOLE VOTING POWER NUMBER OF SHARES				 1,273,400 BENEFICIALLY OWNED 		_____________________________ BY EACH REPORTING PERSON WITH:				(6) SHARED VOTING POWER 					 	 0 						_____________________________ 					 (7) SOLE DISPOSITIVE POWER 					 1,273,400 					_____________________________ 						(8) SHARED DISPOSITIVE POWER 						 23,379 						_____________________________ (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 			 1,296,779 ----------------------------------------------------------------------------- (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS) [_] ----------------------------------------------------------------------------- (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 			 5.84 % ----------------------------------------------------------------------------- (12) TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) 			 HC 				Page 3 of 8 pages ============================================================================= ----------------------------------------------------------------------------- CUSIP NO. 37953G103			13G		 Page 4 of 8 Pages ----------------------------------------------------------------------------- Item 1. (a) Name of Issuer 	GLOBAL BRASS AND COPPER HOLDINGS, INC. (b)	Address of Issuer's Principal Executive Offices. 	 475 N. Martingale Road Suite 1200, Schaumburg, IL 60173 Item 2. (a)	Name of Person Filing: 	 This Schedule 13G is being filed by Renaissance Technologies LLC ("RTC") and Renaissance Technologies Holdings Corporation ("RTHC"). (b) Address of Principal Business Office or, if none, Residence. 	 The principal business address of the reporting persons is: 800 Third Avenue New York, New York 10022 (c) Citizenship. 	RTC is a Delaware limited liability company, and 	RTHC is a Delaware corporation. (d) Title of Class of Securities. 	 common stock (e) CUSIP Number. 	 37953G103 					Page 4 of 8 pages ============================================================================= Item 3. If this statement is filed pursuant to Rule 13d-1(b) or 13-d-2(b) 	or (c),check whether the person filing is a: (a) [_] Broker or dealer registered under section 15 of the Act. (b) [_] Bank as defined in section 3(a)(6) of the Act. (c) [_] Insurance Company as defined in section 3(a)(19) of the Act. (d) [_] Investment Company registered under section 8 of the Investment 	 Company Act. (e) [x] Investment Adviser in accordance with Sec.240.13d-1(b)(1)(ii)(E). (f) [_] Employee Benefit Plan or Endowment Fund in accordance with Sec. 240.13d-1(b)(1)(ii)(F). (g) [_] Parent holding company, in accordance with Sec.240.13d-1(b)(1)(ii)(G). (h) [_] A savings associations as defined in Section 3(b) of the Federal 	 Deposit Insurance Act. (i) [_] A church plan that is excluded from the definition of an investment 	 company under section 3(c)(14) of the Investment Company Act of 1940. (j) [_] Group, in accordance with Sec.240.13d-1(b)(1)(ii)(J). Item 4. Ownership. (a) Amount beneficially owned. 	RTC: 	 1,296,779	shares 	RTHC:	 1,296,779	shares, comprising the shares beneficially owned 			by RTHC, because of RTHC's majority ownership of RTC. (b) Percent of Class. 	RTC: 	5.84 % 	RTHC:	5.84 % (c) Number of shares as to which the person has: (i) sole power to vote or to direct the vote: 	 RTC: 1,273,400 	 RTHC: 1,273,400 (ii) Shared power to vote or to direct the vote:	0 (iii) sole power to dispose or to direct the disposition of: 		RTC:	1,273,400 		RTHC:	1,273,400 (iv) Shared power to dispose or to direct the disposition of: 		RTC: 	23,379 		RTHC:	23,379 					Page 5 of 8 pages ============================================================================= Item 5. Ownership of Five Percent or Less of a Class. 	If this statement is being filed to report the fact that as of the 	date hereof the reporting person has ceased to be the beneficial 	owner of more than five percent of the class of securities, 	check the following: [_] Item 6. Ownership of More than Five Percent on Behalf of Another Person. 	Certain funds and accounts managed by RTC have the right to receive 	dividends and proceeds from the sale of the securities which are 	the subject of this report. Item 7. Identification and Classification of the Subsidiary Which Acquired 	the Security Being Reported on by the Parent Holding Company. 	 Not applicable Item 8. Identification and Classification of Members of the Group. 	 Not applicable Item 9. Notice of Dissolution of a Group. 	 Not applicable 					Page 6 of 8 pages ============================================================================= Item 10. Certification By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. SIGNATURE After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. Date: February 12, 2019 Renaissance Technologies LLC By: /s/ Mark Silber Executive Vice President 			 Renaissance Technologies Holdings Corporation 			 By: /s/ Mark Silber 				 Vice President Attention: Intentional misstatements or omissions of fact constitute Federal criminal violations (See 18 U.S.C. 1001). 					Page 7 of 8 Pages ============================================================================== 				EXHIBIT 99.1 		AGREEMENT REGARDING JOINT FILING 		UNDER RULE 13D-1(K) OF THE EXCHANGE ACT In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, each of the undersigned agrees to the filing on behalf of each of a Statement on Schedule 13G, and all amendments thereto, with respect to the shares of common stock of GLOBAL BRASS AND COPPER HOLDINGS, INC. Date: February 12, 2019 Renaissance Technologies LLC By: /s/ Mark Silber Executive Vice President 					Renaissance Technologies Holdings Corporation 			 		 By: /s/ Mark Silber 					 Vice President 					Page 8 of 8 Pages