CDLX

SEC source: 0000899243-19-020425 · doc4.xml · nonDerivative · entry 2

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,058,312

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.50 to $29.49, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020510 · doc4.xml · nonDerivative · entry 1

Canaan VIII LP · CIK 0001419148 · Director

Canaan Partners VIII LLC · CIK 0001552200 · Director

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 187,683

F1 · kind: On July 24, 2019, Canaan VIII L.P. (the "Canaan Fund") distributed, for no consideration, 570,482 shares of Common Stock of the Issuer (the "Shares") to its limited partners and to Canaan Partners VIII LLC ("Canaan VIII" and, together with the Canaan Fund, the "Canaan Entities"), the general partner of the Canaan Fund, representing each such partner's pro rata interest in the shares held by the Canaan Fund. On the same date, Canaan VIII distributed, for no consideration, the Shares it received from the distribution to its members in an amount equal to each such member's pro rata interest in the Shares. The aforementioned distributions were made in accordance with the exemptions afforded by Rule 16a-13 and Rule 16a-9 of the Securities Exchange Act of 1934, as amended.

F1 · price: On July 24, 2019, Canaan VIII L.P. (the "Canaan Fund") distributed, for no consideration, 570,482 shares of Common Stock of the Issuer (the "Shares") to its limited partners and to Canaan Partners VIII LLC ("Canaan VIII" and, together with the Canaan Fund, the "Canaan Entities"), the general partner of the Canaan Fund, representing each such partner's pro rata interest in the shares held by the Canaan Fund. On the same date, Canaan VIII distributed, for no consideration, the Shares it received from the distribution to its members in an amount equal to each such member's pro rata interest in the Shares. The aforementioned distributions were made in accordance with the exemptions afforded by Rule 16a-13 and Rule 16a-9 of the Securities Exchange Act of 1934, as amended.

F2 · ownership.direct: Shares held directly by the Canaan Fund. Canaan VIII is the sole general partner of the Canaan Fund and may be deemed to have sole voting, investment and dispositive power with respect to the shares held by the Canaan Fund. John Balen is a manager and member of Canaan VIII. Investment and voting decisions with respect to the shares held by the Canaan Fund are made by the managers of Canaan VIII, collectively. Canaan VIII disclaims Section 16 beneficial ownership of the shares held by the Canaan Fund, except to the extent, if any, of its pecuniary interest therein.

SEC source: 0000899243-19-020425 · doc4.xml · nonDerivative · entry 13

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 20,989

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.545 to $28.61, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F9 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020425 · doc4.xml · nonDerivative · entry 9

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,362

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.545 to $28.61, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020425 · doc4.xml · nonDerivative · entry 5

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 40,866

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.545 to $28.61, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020425 · doc4.xml · nonDerivative · entry 1

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,097,054

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.545 to $28.61, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0001666071-19-000069 · wf-form4_156389015632680.xml · nonDerivative · entry 4

Laube Lynne Marie · CIK 0001730687 · Director · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 42,215

F7 · kind: These sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the trustees of the 2013 Lynne Marie Laube GRAT fbo Hayley Marie Allbright (the "HMA GRAT") on May 14, 2019.

F5 · price: The price reported is a weighted average sales price. These shares were sold in multiple transactions at prices ranging from $26.81 to $27.66, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (4) to this Form 4.

F8 · ownership.nature: The reportable securities are held by the 2013 Lynne Marie Laube GRAT fbo Hayley Marie Allbright (the "HMA GRAT"). The Reporting Person is the trustee of the HMA GRAT.

SEC source: 0001666071-19-000069 · wf-form4_156389015632680.xml · nonDerivative · entry 3

Laube Lynne Marie · CIK 0001730687 · Director · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 42,215

F4 · kind: These sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the trustees of the 2013 Lynne Marie Laube GRAT fbo Keegan George Allbright (the "KGA GRAT") on May 14, 2019.

F5 · price: The price reported is a weighted average sales price. These shares were sold in multiple transactions at prices ranging from $26.81 to $27.66, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (4) to this Form 4.

F6 · ownership.nature: The reportable securities are held by the 2013 Lynne Marie Laube GRAT fbo Keegan George Allbright (the "KGA GRAT"). The Reporting Person is the trustee of the KGA GRAT.

SEC source: 0001666071-19-000069 · wf-form4_156389015632680.xml · nonDerivative · entry 2

Laube Lynne Marie · CIK 0001730687 · Director · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 463,677

F1 · kind: These sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 5, 2018, as amended May 14, 2019.

F3 · price: The price reported is a weighted average sales price. These shares were sold in multiple transactions at prices ranging from $27.50 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (3) to this Form 4.

SEC source: 0001666071-19-000069 · wf-form4_156389015632680.xml · nonDerivative · entry 1

Laube Lynne Marie · CIK 0001730687 · Director · Chief Operating Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 464,557

F1 · kind: These sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 5, 2018, as amended May 14, 2019.

F2 · price: The price reported is a weighted average sales price. These shares were sold in multiple transactions at prices ranging from $26.50 to $27.48, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (2) to this Form 4.

SEC source: 0001666071-19-000070 · wf-form4_156400150426705.xml · nonDerivative · entry 1

SOMERS KIRK · CIK 0001204015 · Chief Legal & Privacy Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 37,783

F1 · kind: These sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2019.

F2 · price: The price reported is a weighted average sales price. These shares were sold in multiple transactions at prices ranging from $27.41 to $27.48, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote (2) to this Form 4.

SEC source: 0000899243-19-020032 · doc4.xml · nonDerivative · entry 8

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,000

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.50 to $28.55, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020032 · doc4.xml · nonDerivative · entry 6

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,369

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.50 to $28.55, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020032 · doc4.xml · nonDerivative · entry 4

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 40,887

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.50 to $28.55, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F5 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020032 · doc4.xml · nonDerivative · entry 2

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,098,115

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.50 to $28.55, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020032 · doc4.xml · nonDerivative · entry 7

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,029

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.28 to $28.15, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020032 · doc4.xml · nonDerivative · entry 5

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,388

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.28 to $28.15, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020032 · doc4.xml · nonDerivative · entry 3

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 40,943

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.28 to $28.15, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F5 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020032 · doc4.xml · nonDerivative · entry 1

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,100,982

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.28 to $28.15, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 12

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,331

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 9

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,595

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 6

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 41,532

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 3

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,131,187

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Bryce Youngren ("Youngren"), a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 12

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,331

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 9

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,595

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 6

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 41,532

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 3

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,131,187

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020739 · doc4a.xml · nonDerivative · entry 12

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,331

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F9 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020739 · doc4a.xml · nonDerivative · entry 9

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,595

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020739 · doc4a.xml · nonDerivative · entry 6

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 41,532

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F7 · shares: The number of shares reported in Column 4 of the original Form 4 was incorrect due to a scrivener's error.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020739 · doc4a.xml · nonDerivative · entry 3

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,131,187

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F5 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.13 to $27.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (5) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 11

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,599

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 8

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,778

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 5

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 42,054

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 2

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,157,965

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Bryce Youngren ("Youngren"), a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 11

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,599

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 8

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,778

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 5

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 42,054

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 2

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,157,965

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020739 · doc4a.xml · nonDerivative · entry 11

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,599

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F9 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020739 · doc4a.xml · nonDerivative · entry 8

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,778

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020739 · doc4a.xml · nonDerivative · entry 5

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 42,054

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-020739 · doc4a.xml · nonDerivative · entry 2

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,157,965

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F4 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.4 to $28.235, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0001666071-19-000066 · wf-form4_156322823672024.xml · nonDerivative · entry 1

Evans David Thomas · CIK 0001730451 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 35,127

F1 · kind: These sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on December 13, 2018

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 10

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,801

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.335 to $28.185, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 7

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,917

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.335 to $28.185, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 4

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 42,448

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.335 to $28.185, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F6 · ownership.nature: The reportable securities are owned directly by PVPE V. PVM V is the general partner of PVPE V. Youngren, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPE V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019789 · doc4.xml · nonDerivative · entry 1

Polaris Venture Management Co. V, L.L.C. · CIK 0001439589 · 10% owner

Polaris Venture Partners V, L.P. · CIK 0001439590 · 10% owner

Polaris Venture Partners Entrepreneurs' Fund V, L.P. · CIK 0001439587 · 10% owner

Polaris Venture Partners Founders' Fund V, L.P. · CIK 0001439588 · 10% owner

Polaris Venture Partners Special Founders' Fund V, L.P. · CIK 0001439586 · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 2,178,192

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.335 to $28.185, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F3 · ownership.nature: The reportable securities are owned directly by PVP V. Polaris Venture Management Co. V, L.L.C. ("PVM V") is the general partner of PVP V. Bryce Youngren ("Youngren"), a member of the Issuer's Board of Directors, is a member of PVM V. Each of Jonathan A. Flint ("Flint") and Terrance G. McGuire ("McGuire") are the managing members of PVM V. Each of Flint, McGuire and Youngren, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVP V. Each of PVM V, Flint, McGuire and Youngren disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 10

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 21,801

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.335 to $28.185, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F8 · ownership.nature: The reportable securities are owned directly by PVPSFF V. PVM V is the general partner of PVPSFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPSFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.

SEC source: 0000899243-19-019787 · doc4.xml · nonDerivative · entry 7

Youngren Bryce · CIK 0001489625 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 14,917

F1 · kind: The sale of these shares were effected pursuant to Rule 10b5-1 trading plans adopted by each of Polaris Venture Partners V, L.P. ("PVP V"), Polaris Venture Partners Entrepreneurs' Fund V, L.P. ("PVPE V"), Polaris Venture Partners Founders' Fund V, L.P. ("PVPFF V") and Polaris Venture Partners Special Founders' Fund V, L.P. ("PVPSFF V") on June 14, 2019.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $27.335 to $28.185, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

F7 · ownership.nature: The reportable securities are owned directly by PVPFF V. PVM V is the general partner of PVPFF V. The Reporting Person, a member of the Issuer's Board of Directors, is a member of PVM V. Each of Flint and McGuire are the managing members of PVM V. Each of Flint, McGuire and the Reporting Person, in their respective capacities with respect to PVM V, may be deemed to have shared voting and dispositive power over the shares held by PVPFF V. Each of PVM V, Flint, McGuire and the Reporting Person disclaims beneficial ownership of these securities and this report shall not be deemed an admission that any one of them is the beneficial owner of such securities for purposes of Section 16 or for any other purpose, except to the extent of their respective pecuniary interests therein.