X0306 4 2020-06-18 0 0001764925 Slack Technologies, Inc. WORK 0001601528 Accel Growth Fund III L.P. 500 UNIVERSITY AVENUE PALO ALTO CA 94301 0 0 1 0 0001605863 Accel Growth Fund III Strategic Partners L.P. 500 UNIVERSITY AVENUE PALO ALTO CA 94301 0 0 1 0 0001601529 Accel Growth Fund III Associates L.L.C. 500 UNIVERSITY AVENUE PALO ALTO CA 94301 0 0 1 0 0001630897 Accel Growth Fund Investors 2014 L.L.C. 500 UNIVERSITY AVENUE PALO ALTO CA 94301 0 0 1 0 Class A Common Stock 2020-06-18 4 C 0 3703796 0.00 A 7409325 D Class A Common Stock 2020-06-18 4 J 0 7409325 0.00 D 0 D Class A Common Stock 2020-06-18 4 C 0 174858 0.00 A 349800 I By Accel Growth Fund III Strategic Partners L.P. Class A Common Stock 2020-06-18 4 J 0 349800 0.00 D 0 I By Accel Growth Fund III Strategic Partners L.P. Class A Common Stock 2020-06-18 4 C 0 245378 0.00 A 490875 I By Accel Growth Fund Investors 2014 L.L.C. Class A Common Stock 2020-06-18 4 J 0 490875 0.00 D 0 I By Accel Growth Fund Investors 2014 L.L.C. Class B Common Stock 2020-06-18 4 C 0 3703796 0.00 D Class A Common Stock 3703796 7412791 D Class B Common Stock 2020-06-18 4 C 0 174858 0.00 D Class A Common Stock 174858 349969 I By Accel Growth Fund III Strategic Partners L.P. Class B Common Stock 2020-06-18 4 C 0 245378 0.00 D Class A Common Stock 245378 491114 I By Accel Growth Fund Investors 2014 L.L.C. 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. These shares are held by Accel Growth Fund III L.P. Accel Growth Fund III Associates L.L.C. ("Accel Growth Fund III GP") is the general partner of each of Accel Growth Fund III L.P. and Accel Growth Fund III Strategic Partners L.P. (together, the "Accel Growth Fund III Entities"). Accel Growth Fund III GP has sole voting and dispositive power with regard to the shares held by the Accel Growth Fund III Entities. Accel Growth Fund III GP disclaims Section 16 beneficial ownership over the securities reported herein except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that such reporting person is the beneficial owner of such securities for Section 16 or any other purpose. On June 18, 2020, Accel Growth Fund III L.P. distributed, for no consideration, 7,409,325 shares of Class A common stock of the Issuer (the "Accel Growth Fund III Shares") to its limited partners and to Accel Growth Fund III GP, the general partner of Accel Growth Fund III L.P., representing each such partner's pro rata interest in such Accel Growth Fund III Shares. On the same date, Accel Growth Fund III GP distributed, for no consideration, the Accel Growth Fund III Shares it received in the distribution by Accel Growth Fund III L.P. to its members, representing each such member's pro rata interest in such Accel Growth Fund III Shares. All of the aforementioned distributions were made in accordance with the exemptions afforded by Rules 16a-13 and 16a-9 of the Securities Exchange Act of 1934, as amended. These shares are held by Accel Growth Fund III Strategic Partners L.P. Accel Growth Fund III GP disclaims Section 16 beneficial ownership over the securities reported herein except to the extent of its pecuniary interest therein, if any, and this report shall not be deemed an admission that such reporting person is the beneficial owner of such securities for Section 16 or any other purpose. On June 18, 2020, Accel Growth Fund III Strategic Partners L.P. distributed, for no consideration, 349,800 shares of Class A common stock of the Issuer (the "Accel Growth Fund III Strategic Shares") to its limited partners and to Accel Growth Fund III GP, the general partner of Accel Growth Fund III Strategic Partners L.P., representing each such partner's pro rata interest in such Accel Growth Fund III Strategic Shares. On the same date, Accel Growth Fund III GP distributed, for no consideration, the Accel Growth Fund III Strategic Shares it received in the distribution by the Fund to its members, representing each such member's pro rata interest in such Accel Growth Fund III Strategic Shares. All of the aforementioned distributions were made in accordance with the exemptions afforded by Rules 16a-13 and 16a-9 of the Securities Exchange Act of 1934, as amended. These shares are held by Accel Growth Fund Investors 2014 L.L.C. On June 18, 2020, Accel Growth Fund Investors 2014 L.L.C. distributed, for no consideration, 490,875 shares of Class A common stock of the Issuer (the "Accel Growth Fund 2014 Shares") to its members, representing each such member's pro rata interest in such Accel Growth Fund 2014 Shares. All of the aforementioned distributions were made in accordance with the exemptions afforded by Rules 16a-13 and 16a-9 of the Securities Exchange Act of 1934, as amended. /s/ TRACY L. SEDLOCK, ATTORNEY IN FACT 2020-06-22