Statement of Changes in Beneficial Ownership (4)

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 OF SECURITIES

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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * Henderson Cal	2. Issuer Name and Ticker or Trading Symbol Slack Technologies, Inc. [ WORK ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                    _____ 10% Owner __X__ Officer (give title below)    _____ Other (specify below) Chief Technology Officer
(Last)          (First)          (Middle) C/O SLACK TECHNOLOGIES, INC., 500 HOWARD STREET	3. Date of Earliest Transaction (MM/DD/YYYY) 5/3/2021
(Street) SAN FRANCISCO,, CA 94105 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. 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
Class A Common Stock	5/3/2021		C		5637	A	$0 (1)	45374	D
Class A Common Stock	5/3/2021		S(2)		5637	D	$42.07	39737	D
Class A Common Stock								85655	I	By trust (3)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. 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		7. Title and Amount of Securities Underlying Derivative Security (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
Restricted Stock Units	(4)	5/3/2021		M			11250	(5)	2/26/2026	Class B Common Stock (1)	11250.0	$0 (4)	78750	D
Class B Common Stock	(1)	5/3/2021		M		11250		(1)	(1)	Class A Common Stock	11250.0	$0 (1)	212903	D
Class B Common Stock	(1)	5/3/2021		C			5637	(1)	(1)	Class A Common Stock	5637.0	$0 (1)	207266	D
Class B Common Stock	(1)							(1)	(1)	Class A Common Stock	13218173.0		13218173	I	By trust (3)
Class B Common Stock	(1)							(1)	(1)	Class A Common Stock	68721.0		68721	I	By trust (6)
Class B Common Stock	(1)							(1)	(1)	Class A Common Stock	222200.0		222200	I	By trust (7)
Class B Common Stock	(1)							(1)	(1)	Class A Common Stock	222200.0		222200	I	By trust (8)
Class B Common Stock	(1)							(1)	(1)	Class A Common Stock	68721.0		68721	I	By trust (9)(10)
Class B Common Stock	(1)							(1)	(1)	Class A Common Stock	222200.0		222200	I	By trust (10)(11)
Class B Common Stock	(1)							(1)	(1)	Class A Common Stock	222200.0		222200	I	By trust (10)(12)
Class B Common Stock	(1)							(1)	(1)	Class A Common Stock	30044.0		30044	I	See footnote (13)

Explanation of Responses:
(1)	Each share of Class B Common Stock is convertible without payment or consideration into one share of Class A Common Stock at the option of the holder and has no expiration date.
(2)	Shares sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of Restricted Stock Units (RSUs).
(3)	Shares held of record by Cal Henderson and Rebecca Reeve Henderson, spouse of the Reporting Person, Trustees of The Henderson Family Trust u/a/d/ 7/21/2016.
(4)	Each RSU represents the right to receive one share of Class B Common Stock.
(5)	The RSUs are subject to time-based and performance-based vesting criteria. The time-based vesting occurs in 16 equal quarterly installments commencing on May 1, 2019, subject to the Reporting Person's continued service with the Issuer on each such date. The performance-based criteria was satisfied upon the Issuer's listing and public trading of its of Class A Common Stock on June 20, 2019.
(6)	Shares held of record by Cal Henderson, Trustee of The Cal Henderson 2019 Grantor Retained Annuity Trust dated May 22, 2019.
(7)	Shares held of record by First Republic Trust Company of Delaware LLC and Cal Henderson, Trustees of The Theodore Henderson GST Exempt Trust under the Cal Henderson Family 2019 Irrevocable Trust dated May 22, 2019.
(8)	Shares held of record by First Republic Trust Company of Delaware LLC and Cal Henderson, Trustees of The William Franklin Henderson GST Exempt Trust under the Cal Henderson Family 2019 Irrevocable Trust dated May 22, 2019.
(9)	Shares held of record by Rebecca Reeve Henderson, Trustee of The Rebecca Reeve Henderson 2019 Grantor Retained Annuity Trust dated May 22, 2019.
(10)	Shares held of record by Rebecca Reeve Henderson, Trustee of The Rebecca Reeve Henderson 2019 Grantor Retained Annuity Trust dated May 22, 2019; Trustee of the Theodore Henderson GST Exempt Trust under the Rebecca Reeve Henderson Family 2019 Irrevocable Trust dated May 22, 2019; Trustee of the William Franklin Henderson GST Exempt Trust under Rebecca Reeve Henderson Family 2019 Irrevocable Trust dated May 22, 2019; and spouse of the Reporting Person, and as such, may be deemed to be beneficially held by the Reporting Person.
(11)	Shares held of record by First Republic Trust Company of Delaware LLC and Rebecca Reeve Henderson, Trustees of The Theodore Henderson GST Exempt Trust under the Rebecca Reeve Henderson Family 2019 Irrevocable Trust dated May 22, 2019.
(12)	Shares held of record by First Republic Trust Company of Delaware LLC and Rebecca Reeve Henderson, Trustees of The William Franklin Henderson GST Exempt Trust under the Rebecca Reeve Henderson Family 2019 Irrevocable Trust dated May 22, 2019.
(13)	Shares held of record by Rebecca Reeve Henderson, spouse of the Reporting Person, and as such, may be deemed to be beneficially held by the Reporting Person.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Henderson Cal C/O SLACK TECHNOLOGIES, INC. 500 HOWARD STREET SAN FRANCISCO,, CA 94105			Chief Technology Officer

Signatures
/s/ David Schellhase, as Attorney-in-Fact		5/5/2021
**Signature of Reporting Person		Date