SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G/A

Under the Securities Exchange Act of 1934
(Amendment No. 1)*

JA Solar Holdings Co., Ltd.
(Name of Issuer)

Ordinary Shares, par value $0.0001 per share
(Title of Class of Securities)

466090206**
(CUSIP Number)

December 31, 2017
(Date of Event Which Requires Filing of This Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨	Rule 13d-1(b)
ý	Rule 13d-1(c)
¨	Rule 13d-1(d)

(Page 1 of 7 Pages)

______________________________

*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.

**There is no CUSIP number assigned to the Ordinary Shares. CUSIP number 466090206 has been assigned to the American Depositary Receipts ("ADRs") of the Company, which are quoted on The NASDAQ Global Select Market under the symbol "JASO." Each ADR represents 5 Ordinary Shares.

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. 466090206

13G/A

Page 2 of 7 Pages

1	NAME OF REPORTING PERSON Numeric Investors LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 0
	6	SHARED VOTING POWER 13,608,315 Ordinary Shares
	7	SOLE DISPOSITIVE POWER 0
	8	SHARED DISPOSITIVE POWER 13,608,315 Ordinary Shares
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 13,608,315 Ordinary Shares
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.72%
12	TYPE OF REPORTING PERSON OO

CUSIP No. 466090206

13G/A

Page 3 of 7 Pages

1	NAME OF REPORTING PERSON Man Group plc
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION United Kingdom
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	5	SOLE VOTING POWER 0
	6	SHARED VOTING POWER 13,608,315 Ordinary Shares
	7	SOLE DISPOSITIVE POWER 0
	8	SHARED DISPOSITIVE POWER 13,608,315 Ordinary Shares
9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 13,608,315 Ordinary Shares
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES			¨
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 5.72%
12	TYPE OF REPORTING PERSON OO, HC

CUSIP No. 466090206

13G/A

Page 4 of 7 Pages

Item 1(a).	NAME OF ISSUER:

	The name of the issuer is JA Solar Holdings Co., Ltd., a Cayman Islands company (the "Company").

Item 1(b).	ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:

	The Company's principal executive offices are located at Building No.8, Noble Center, Automobile Museum East Road, Fengtai, Beijing 100070, The People’s Republic of China.

Item 2(a).	NAME OF PERSON FILING:

	This statement is filed by the entities and persons listed below, who are collectively referred to herein as the "Reporting Persons" with respect to the Ordinary Shares (as defined in Item 2(d) below):

	Investment Manager:

	(i)	Numeric Investors LLC (the "Investment Manager"), with respect to the Ordinary Shares held by certain funds and/or managed accounts to which the Investment Manager serves as investment manager (collectively, the "Numeric Funds").

	Parent Company:

	(ii)	Man Group plc (the "Parent Company"), which indirectly, through various intermediate entities, controls the Investment Manager, with respect to the Ordinary Shares held by each of the Numeric Funds.

Item 2(b).	ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE:
Item 2(c).	CITIZENSHIP:

	This statement is filed by:

	(i)	Numeric Investors LLC 470 Atlantic Avenue,6th Floor Boston, MA 02210 Citizenship: State of Delaware

	(ii)	Man Group Plc Riverbank House 2 Swan Lane London EC4R 3AD United Kingdom Citizenship: United Kingdom

Item 2(d).	TITLE OF CLASS OF SECURITIES:

	Ordinary Shares, par value $0.0001 per share (the "Ordinary Shares").

CUSIP No. 466090206

13G/A

Page 5 of 7 Pages

Item 2(e).	CUSIP NUMBER:

	There is no CUSIP number assigned to the Ordinary Shares. CUSIP number 466090206 has been assigned to the ADRs of the Company, which are quoted on The NASDAQ Global Select Market under the symbol "JASO." Each ADR represents 5 Ordinary Shares.

Item 3.	IF THIS STATEMENT IS FILED PURSUANT TO RULES 13d-1(b) OR 13d-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 of 1940,
	(e)	¨	An investment adviser in accordance with Rule 13d-1(b)(1)(ii)(E);
	(f)	¨	Employee Benefit Plan or Endowment Fund in accordance with Rule 13d-1(b)(1)(ii)(F),
	(g)	¨	Parent Holding Company or control person in accordance with Rule 13d-1(b)(1)(ii)(G),
	(h)	¨	Savings Association 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;
	(j)	¨	A non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J);
	(k)	¨	Group, in accordance with Rule 13d-1(b)(1)(ii)(K).

If filing as a non-U.S. institution in accordance with Rule 13d-1(b)(1)(ii)(J), please

specify the type of institution:____________________________________

Item 4.	OWNERSHIP

	The information required by Items 4(a) – (c) is set forth in Rows (5) – (11) of the cover page for each Reporting Person hereto and is incorporated herein by reference for each such Reporting Person. The percentage set forth in Row (11) of the cover page for each Reporting Person is based on the 237,923,602 Ordinary Shares outstanding as of November 15, 2017, as reported in Exhibit 99.2 of the Company's Report of Foreign Private Issuer on Form 6-K filed with the Securities and Exchange Commission on November 20, 2017.

CUSIP No. 466090206

13G/A

Page 6 of 7 Pages

The Investment Manager, which serves as the investment manager to each of the Numeric Funds, may be deemed to be the beneficial owner of all of the Ordinary Shares owned by the Numeric Funds. The Parent Company, which indirectly, through various intermediate entities, controls the Investment Manager, may be deemed to be the beneficial owner of all the Ordinary Shares owned by the Numeric Funds. The Parent Company hereby disclaims any beneficial ownership of any such Ordinary Shares.

Item 5.	OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.

	Not applicable.

Item 6.	OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.

	See Item 2.

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 GROUP.

	Not applicable.

Item 10.

CERTIFICATION.

	Each of the Reporting Persons hereby makes the following certification:

	By signing below each Reporting Person certifies that, to the best of its knowledge and belief, the securities referred to above were 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.

CUSIP No. 466090206

13G/A

Page 7 of 7 Pages

SIGNATURES

After reasonable inquiry and to the best of its knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

DATE: February 9, 2018

NUMERIC INVESTORS LLC


By: /s/ Christopher Ancona
Name: Christopher Ancona
Title: Chief Compliance Officer

MAN GROUP PLC


By: /s/ Michelle Robyn Grew
Name: Michelle Robyn Grew
Title: Chief Administrative Officer

JA Solar Holdings Co., Ltd. SC 13G/A