X0306 4 2019-03-04 0 0001751299 Kaleido Biosciences, Inc. KLDO 0001724575 Flagship Ventures Fund V General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 1 0 1 0 0001627639 Flagship Ventures Fund V, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001724959 Flagship VentureLabs V LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001768987 Flagship VentureLabs V Manager LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001400240 Flagship Pioneering Inc. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001725001 Nutritional Health Disruptive Innovation Fund, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001725000 Nutritional Health Side Fund, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001677345 Flagship Ventures Opportunities Fund I, L.P. 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001725004 Flagship Ventures Opportunities Fund I General Partner LLC 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 0 0 1 0 0001222012 AFEYAN NOUBAR 55 CAMBRIDGE PARKWAY, SUITE 800E CAMBRIDGE MA 02142 1 0 1 0 Common Stock 2500000 I See Footnote Common Stock 2019-03-04 4 C 0 1545852 A 1545852 I See Footnote Common Stock 2019-03-04 4 C 0 4637555 A 4637555 I See Footnote Common Stock 2019-03-04 4 C 0 426240 A 1972092 I See Footnote Common Stock 2019-03-04 4 C 0 639360 A 639360 I See Footnote Common Stock 2019-03-04 4 C 0 321337 A 2293429 I See Footnote Common Stock 2019-03-04 4 C 0 964010 A 5601565 I See Footnote Common Stock 2019-03-04 4 C 0 1285347 A 1285347 I See Footnote Common Stock 2019-03-04 4 C 0 625625 A 6227190 I See Footnote Common Stock 2019-03-04 4 C 0 625625 A 1910972 I See Footnote Common Stock 2019-03-04 4 P 0 266667 15.00 A 2560096 I See Footnote Common Stock 2019-03-04 4 P 0 333333 15.00 A 6560523 I See Footnote Common Stock 2019-03-04 4 P 0 333333 15.00 A 2244305 I See Footnote Series A Preferred Stock 2019-03-04 4 C 0 3091704 D Common Stock 1545852 0 I See Footnote Series A Preferred Stock 2019-03-04 4 C 0 9275111 D Common Stock 4637555 0 I See Footnote Series A-1 Preferred Stock 2019-03-04 4 C 0 852480 D Common Stock 426240 0 I See Footnote Series A-1 Preferred Stock 2019-03-04 4 C 0 1278720 D Common Stock 639360 0 I See Footnote Series B Preferred Stock 2019-03-04 4 C 0 642674 D Common Stock 321337 0 I See Footnote Series B Preferred Stock 2019-03-04 4 C 0 1928021 D Common Stock 964010 0 I See Footnote Series B Preferred Stock 2019-03-04 4 C 0 2570694 D Common Stock 1285347 0 I See Footnote Series C Preferred Stock 2019-03-04 4 C 0 1251251 D Common Stock 625625 0 I See Footnote Series C Preferred Stock 2019-03-04 4 C 0 1251251 D Common Stock 625625 0 I See Footnote Shares held by Flagship VentureLabs V LLC ("VentureLabs V"). Flagship Ventures Fund V, L.P. ("Flagship Fund V") is a member of VentureLabs V. Flagship Ventures Fund V General Partner LLC ("Flagship Fund V GP") is the general partner of Flagship Fund V. Flagship VentureLabs V Manager LLC ("VentureLabs V Manager") serves as manager of VentureLabs V. Flagship Pioneering, Inc. ("Flagship Pioneering") is the manager of VentureLabs V Manager. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Fund V GP and as sole director of Flagship Pioneering. Each of these entities and Noubar B. Afeyan, Ph.D. may be deemed to share voting and investment power with respect to all shares held by VentureLabs V. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. Each share of Series A Preferred Stock converted into shares of the Issuer's common stock, par value $0.001 ("Common Stock"), on a one-for-two basis upon the closing of the Issuer's initial public offering. Shares held by Flagship Fund V. Flagship Fund V GP is the general partner of Flagship Fund V. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Fund V GP and may be deemed to possess sole voting and investment power with respect to all shares held by Flagship Fund V. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. Shares held by Nutritional Health Disruptive Innovation Fund, L.P. ("Nutritional Innovation Fund"). Flagship Fund V GP is the general partner of Nutritional Innovation Fund. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Fund V GP and may be deemed to possess sole voting and investment power with respect to all shares held by Nutritional Innovation Fund. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. Each share of Series A-1 Preferred Stock converted into shares of the Issuer's Common Stock on a one-for-two basis upon the closing of the Issuer's initial public offering. Shares held by Nutritional Health Side Fund, L.P. ("Nutritional Health Side Fund"). Flagship Fund V GP is the general partner of Nutritional Health Side Fund. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Fund V GP and may be deemed to possess sole voting and investment power with respect to all shares held by Nutritional Health Side Fund. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. Each share of Series B Preferred Stock converted into shares of the Issuer's Common Stock on a one-for-two basis upon the closing of the Issuer's initial public offering. Each share of Series C Preferred Stock converted into shares of the Issuer's Common Stock on a one-for-two basis upon the closing of the Issuer's initial public offering. Shares held by Flagship Ventures Opportunities Fund I, L.P. ("Flagship Opportunities I"). Flagship Ventures Opportunities Fund I General Partner LLC ("Flagship Opportunities GP") is the general partner of Flagship Opportunities I. Noubar B. Afeyan, Ph.D. serves as sole manager of Flagship Opportunities GP and may be deemed to possess sole voting and investment power with respect to all shares held by Flagship Opportunities I. Each of the reporting persons disclaims beneficial ownership of the shares except to the extent of his or its pecuniary interest therein. Due to limitations of the electronic filing system, each of Flagship Ventures Fund IV General Partner LLC, Flagship Ventures Fund IV, L.P., Flagship VentureLabs IV LLC, Flagship Ventures 2007 General Partner LLC, Flagship Ventures Fund 2007, L.P., Cadena LLC, Edwin M. Kania Jr. and Noubar B. Afeyan, Ph.D. are filing a separate Form 4 with respect to securities of the Issuer. Flagship Ventures Fund V General Partner LLC, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 2019-03-06 Flagship Ventures Fund V, L.P., By: Flagship Ventures Fund V General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 2019-03-06 Flagship Pioneering, Inc., By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Sole Director 2019-03-06 Flagship VentureLabs V Manager LLC, By: Flagship Pioneering, Inc., its manager, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Sole Director 2019-03-06 Flagship VentureLabs V LLC, By: Flagship VentureLabs V Manager LLC, its manager, By: Flagship Pioneering, Inc., its manager, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Sole Director 2019-03-06 Nutritional Health Disruptive Innovation Fund, L.P., By: Flagship Ventures Fund V General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 2019-03-06 Nutritional Health Side Fund, L.P., By: Flagship Ventures Fund V General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 2019-03-06 Flagship Ventures Opportunities Fund I General Partner LLC, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 2019-03-06 Flagship Ventures Opportunities Fund I, L.P., By: Flagship Ventures Opportunities Fund I General Partner LLC, its general partner, By: /s/ Noubar B. Afeyan, Name: Noubar B. Afeyan, Ph.D., Title: Manager 2019-03-06 Noubar B. Afeyan, Ph.D., By: /s/ Noubar B. Afeyan 2019-03-06