SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934
(Amendment No. 2)*

Cimarex Energy Co.
(Name of Issuer)

Common Stock, par value $0.01 per share
(Title of Class of Securities)

171798101
(CUSIP Number)

Robert Atchinson
Adage Capital Partners GP, L.L.C.
200 Clarendon Street, 52nd Floor
Boston, MA 02116
(617) 867-2800
(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

October 1, 2021
(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), Rule 13d-1(f) or Rule 13d-1(g), check the following box. [ ]

(Page 1 of 10 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 disclosures provided in a prior cover page.

The information required on 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. 171798101

SCHEDULE 13D/A

Page 2 of 10 Pages

1	NAME OF REPORTING PERSON Adage Capital Partners, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	SOURCE OF FUNDS WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	7	SOLE VOTING POWER -0-
	8	SHARED VOTING POWER -0-
	9	SOLE DISPOSITIVE POWER -0-
	10	SHARED DISPOSITIVE POWER -0-
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON -0-
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0%
14	TYPE OF REPORTING PERSON PN

CUSIP No. 171798101

SCHEDULE 13D/A

Page 3 of 10 Pages

1	NAME OF REPORTING PERSON Adage Capital Partners GP, L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	SOURCE OF FUNDS AF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	7	SOLE VOTING POWER -0-
	8	SHARED VOTING POWER -0-
	9	SOLE DISPOSITIVE POWER -0-
	10	SHARED DISPOSITIVE POWER -0-
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON -0-
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0%
14	TYPE OF REPORTING PERSON OO

CUSIP No. 171798101

SCHEDULE 13D/A

Page 4 of 10 Pages

1	NAME OF REPORTING PERSON Adage Capital Advisors, L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	SOURCE OF FUNDS AF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	7	SOLE VOTING POWER -0-
	8	SHARED VOTING POWER -0-
	9	SOLE DISPOSITIVE POWER -0-
	10	SHARED DISPOSITIVE POWER -0-
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON -0-
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0%
14	TYPE OF REPORTING PERSON OO

CUSIP No. 171798101

SCHEDULE 13D/A

Page 5 of 10 Pages

1	NAME OF REPORTING PERSON Robert Atchinson
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	SOURCE OF FUNDS AF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	7	SOLE VOTING POWER -0-
	8	SHARED VOTING POWER -0-
	9	SOLE DISPOSITIVE POWER -0-
	10	SHARED DISPOSITIVE POWER -0-
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON -0-
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0%
14	TYPE OF REPORTING PERSON IN

CUSIP No. 171798101

SCHEDULE 13D/A

Page 6 of 10 Pages

1	NAME OF REPORTING PERSON Phillip Gross
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) ¨ (b) ¨
3	SEC USE ONLY
4	SOURCE OF FUNDS AF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH:	7	SOLE VOTING POWER -0-
	8	SHARED VOTING POWER -0-
	9	SOLE DISPOSITIVE POWER -0-
	10	SHARED DISPOSITIVE POWER -0-
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON -0-
12	CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES			¨
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0%
14	TYPE OF REPORTING PERSON IN

CUSIP No. 171798101

SCHEDULE 13D/A

Page 7 of 10 Pages

This Amendment No. 2 ("Amendment No. 2") amends and supplements the statement on Schedule 13D filed with the Securities and Exchange Commission (the "SEC") on June 14, 2021 (the "Original Schedule 13D"), as amended by Amendment No. 1 filed with the SEC on July 8, 2021 ("Amendment No. 1" and together with the Original Schedule 13D and this Amendment No. 2, the "Schedule 13D") with respect to the shares of Common Stock, $0.01 par value per share (the "Common Stock"), of Cimarex Energy Co., a Delaware corporation (the "Issuer"). This Amendment No. 2 amends Item 5 as set forth below. This is the final amendment to the Schedule 13D and constitutes an "exiting filing" for the Reporting Persons.

Item 5.	INTEREST IN SECURITIES OF THE ISSUER
	Item 5 of the Schedule 13D is hereby amended and restated as follows:
(a)	See rows (11) and (13) of the cover pages to this Schedule 13D for the aggregate number of shares of Common Stock and percentages of the shares of Common Stock beneficially owned by each of the Reporting Persons.

(b)	See rows (7) through (10) of the cover pages to this Schedule 13D for the number of shares of Common Stock as to which each Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition.

(c)	The transactions in the shares of Common Stock during the past sixty days by ACP, which were all in the open market, are set forth in Schedule A, and are incorporated herein by reference. In addition, on October 1, 2021 ACP disposed of 7,161,946 shares of Common Stock upon the effectiveness of the merger contemplated by the Merger Agreement. At the effective time of such merger, each outstanding share of Common Stock was converted into the right to receive 4.0146 shares of common stock of Cabot Oil & Gas Corporation. The other Reporting Persons did not enter into any transactions in the shares of Common Stock during the past sixty days.

(d)	No person other than the Reporting Persons is known to have the right to receive, or the power to direct the receipt of dividends from, or proceeds from the sale of, such shares of Common Stock.

(e)	October 1, 2021.

CUSIP No. 171798101

SCHEDULE 13D/A

Page 8 of 10 Pages

SIGNATURES

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

Date: October 12, 2021

ADAGE CAPITAL PARTNERS, L.P.
By: Adage Capital Partners GP, L.L.C.,
its general partner

By: Adage Capital Advisors, L.L.C.,
its managing member

/s/ Robert Atchinson
Name: Robert Atchinson
Title: Managing Member

ADAGE CAPITAL PARTNERS GP, L.L.C.
By: Adage Capital Advisors, L.L.C.,
its managing member

/s/ Robert Atchinson
Name: Robert Atchinson
Title: Managing Member

ADAGE CAPITAL ADVISORS, L.L.C.

/s/ Robert Atchinson
Name: Robert Atchinson
Title: Managing Member

/s/ Robert Atchinson
ROBERT ATCHINSON, individually

/s/ Phillip Gross
PHILLIP GROSS, individually

CUSIP No. 171798101

SCHEDULE 13D/A

Page 9 of 10 Pages

Schedule A

This Schedule sets forth information with respect to each purchase and sale of shares of Common Stock which were effectuated by ACP during the past sixty days. All transactions were effectuated in the open market through a broker. The price reported in the column Price Per Share ($) is a weighted average price if a price range is indicated in the column Price Range ($). These shares of Common Stock were purchased/sold in multiple transactions at prices between the price ranges below. The Reporting Persons will undertake to provide to the staff of the SEC, upon request, full information regarding the number of shares of Common Stock sold at each separate price.

Trade Date	Shares Purchased (Sold)	Price Per Share ($)*	Price Range ($)*
08/13/2021	(75,000)**	65.3793	65.1871-65.5507
08/16/2021	78,100	62.5994	62.4774-62.6621
08/17/2021	(33,908)	63.2755	62.6279-63.5062
08/18/2021	50,000	60.4437	60.4435-60.4660
08/18/2021	(12,975)	62.6537
08/19/2021	25,000	58.3193
08/25/2021	(17,525)	60.4661	60.3248-60.5725
08/26/2021	(20,000)	60.2733	59.8525-60.6150
08/27/2021	(10,000)	62.0934	62.0000-62.1575
08/27/2021	(20,000)	63.4690	63.0333-63.8497
08/27/2021	50,000	63.8468	63.7670-63.9900
08/30/2021	(50,000)	64.7330	64.4539-65.1820
08/31/2021	8,252	63.6262	63.2999-63.6613
09/01/2021	(25,000)	66.6485	66.2294-66.9012
09/02/2021	7,793	69.9317	69.9300-69.9400
09/02/2021	(52,301)	69.9799	69.8650-70.1075
09/03/2021	(22,699)	70.1161
09/03/2021	(75,000)	71.7090	71.5501-71.7884
09/07/2021	20,410	70.9398
09/07/2021	(75,000)	71.3217	71.0200-71.6750
09/08/2021	79,590	72.4000
09/08/2021	(70,000)	72.7818	72.4962-73.2122
09/08/2021	(5,000)	73.6600
09/09/2021	(25,000)	73.6444	73.6150-73.7496
09/15/2021	8,451	79.5250
09/15/2021	(25,000)	79.6500
09/17/2021	(50,000)	77.7211	77.4993-77.7900
09/17/2021	2,139	77.9425
09/20/2021	283,618	77.0670	76.3700-77.3521
09/20/2021	189,937	77.4217	77.3787-77.4499
09/23/2021	11,000	79.2154

CUSIP No. 171798101

SCHEDULE 13D/A

Page 10 of 10 Pages

09/24/2021	23,000	81.2754
09/24/2021	(50,000)	81.5679	81.2500-81.8650
09/27/2021	61,973	87.3083
09/27/2021	(25,000)	87.4307	87.3079-87.7850
09/27/2021	(25,000)	88.4247	88.3670-88.5009
09/28/2021	(75,000)	88.4465	88.3473-88.6448
09/28/2021	(75,000)	90.1650	89.7771-90.5729
09/29/2021	(50,000)	88.8401	88.4500-89.1283
09/29/2021	(50,000)	90.7931	90.6100-90.9421

* Excluding commissions.

** Short sale.

CIMAREX ENERGY CO SC 13D/A