SC 13G 1 d10927867_13-g.htm

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, DC 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934

(Amendment No.)*

Caribou Biosciences, Inc.

(Name of Issuer)

Common stock, par value $0.0001 per share

(Title of Class of Securities)

142038108

(CUSIP Number)

December 29, 2023

(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)

[X] 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.

142038108

1.	NAME OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

	Avidity Partners Management LP

2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
		(a) [_]
		(b) [X]

3.	SEC USE ONLY



4.	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.	SOLE VOTING POWER

	0

6.	SHARED VOTING POWER

	6,360,212

7.	SOLE DISPOSITIVE POWER

	0

8.	SHARED DISPOSITIVE POWER

	6,360,212

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	6,360,212

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)

	7.2%¹

12.	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IA, PN

¹ The percentage of ownership based on 88,431,136 shares of Common stock of the Issuer outstanding as of November 2, 2023, as reported on the Issuer’s Form 10-Q filed on November 7, 2023.

CUSIP No.

142038108

1.	NAME OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

	Avidity Partners Management (GP) LLC

2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
		(a) [_]
		(b) [X]

3.	SEC USE ONLY


4.	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.	SOLE VOTING POWER

	0

6.	SHARED VOTING POWER

	6,360,212

7.	SOLE DISPOSITIVE POWER

	0

8.	SHARED DISPOSITIVE POWER

	6,360,212

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	6,360,212

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)

	7.2%²

12.	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) OO

² The percentage of ownership based on 88,431,136 shares of Common stock of the Issuer outstanding as of November 2, 2023, as reported on the Issuer’s Form 10-Q filed on November 7, 2023.

CUSIP No.

142038108

1.	NAME OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

	Avidity Capital Partners Fund (GP) LP

2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
		(a) [_]
		(b) [X]

3.	SEC USE ONLY


4.	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.	SOLE VOTING POWER

	0

6.	SHARED VOTING POWER

	6,360,212

7.	SOLE DISPOSITIVE POWER

	0

8.	SHARED DISPOSITIVE POWER

	6,360,212

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	6,360,212

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)

	7.2%³

12.	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) OO, PN

³ The percentage of ownership based on 88,431,136 shares of Common stock of the Issuer outstanding as of November 2, 2023, as reported on the Issuer’s Form 10-Q filed on November 7, 2023.

CUSIP No.

142038108

1.	NAME OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

	Avidity Capital Partners (GP) LLC

2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
		(a) [_]
		(b) [X]

3.	SEC USE ONLY


4.	CITIZENSHIP OR PLACE OF ORGANIZATION

	Delaware

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.	SOLE VOTING POWER

	0

6.	SHARED VOTING POWER

	6,360,212

7.	SOLE DISPOSITIVE POWER

	0

8.	SHARED DISPOSITIVE POWER

	6,360,212

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	6,360,212

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)

	7.2%⁴

12.	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) OO

⁴ The percentage of ownership based on 88,431,136 shares of Common stock of the Issuer outstanding as of November 2, 2023, as reported on the Issuer’s Form 10-Q filed on November 7, 2023.

CUSIP No.

142038108

1.	NAME OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

	Avidity Master Fund LP

2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
		(a) [_]
		(b) [X]

3.	SEC USE ONLY


4.	CITIZENSHIP OR PLACE OF ORGANIZATION

	Cayman Islands

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.	SOLE VOTING POWER

	0

6.	SHARED VOTING POWER

	4,687,000

7.	SOLE DISPOSITIVE POWER

	0

8.	SHARED DISPOSITIVE POWER

	4,687,000

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	4,687,000

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)

	5.3%⁵

12.	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) OO, PN

⁵ The percentage of ownership based on 88,431,136 shares of Common stock of the Issuer outstanding as of November 2, 2023, as reported on the Issuer’s Form 10-Q filed on November 7, 2023.

CUSIP No.

142038108

1.	NAME OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

	David Witzke

2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
		(a) [_]
		(b) [X]

3.	SEC USE ONLY



4.	CITIZENSHIP OR PLACE OF ORGANIZATION

	United States of America

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.	SOLE VOTING POWER

	0

6.	SHARED VOTING POWER

	6,360,212

7.	SOLE DISPOSITIVE POWER

	0

8.	SHARED DISPOSITIVE POWER

	6,360,212

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	6,360,212

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)

	7.2%⁶

12.	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN

⁶ The percentage of ownership based on 88,431,136 shares of Common stock of the Issuer outstanding as of November 2, 2023, as reported on the Issuer’s Form 10-Q filed on November 7, 2023.

CUSIP No.

142038108

1.	NAME OF REPORTING PERSONS
	I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

	Michael Gregory

2.	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS)
		(a) [_]
		(b) [X]

3.	SEC USE ONLY



4.	CITIZENSHIP OR PLACE OF ORGANIZATION

	United States of America

NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH

5.	SOLE VOTING POWER

	0

6.	SHARED VOTING POWER

	6,360,212

7.	SOLE DISPOSITIVE POWER

	0

8.	SHARED DISPOSITIVE POWER

	6,360,212

9.	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

	6,360,212

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)

	7.2%⁷

12.	TYPE OF REPORTING PERSON (SEE INSTRUCTIONS) IN

⁷The percentage of ownership based on 88,431,136 shares of Common stock of the Issuer outstanding as of November 2, 2023, as reported on the Issuer’s Form 10-Q filed on November 7, 2023.

Item 1.	(a).	Name of Issuer:

		Caribou Biosciences, Inc.

(b).

Address of issuer's principal executive offices:

2929 7^th Street, Suite 105

Berkeley, California 94710

Item 2.

(a).

Name of person filing:

Avidity Partners Management LP

Avidity Partners Management (GP) LLC

Avidity Capital Partners Fund (GP) LP

Avidity Capital Partners (GP) LLC

Avidity Master Fund LP

David Witzke

Michael Gregory

(b).

Address or principal business office or, if none, residence:

Avidity Partners Management LP

SEC Form SC 13G filed by Caribou Biosciences Inc.