GWH

SEC source: 0001628280-22-026773 · wf-form4_166631222440268.xml · nonDerivative · entry 2

Moftakhar Amir · CIK 0001884662 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 558,850

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.39 to $3.60, 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.

SEC source: 0001628280-22-026773 · wf-form4_166631222440268.xml · nonDerivative · entry 1

Moftakhar Amir · CIK 0001884662 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 563,043

F1 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.39 to $3.60, 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.

SEC source: 0001628280-22-026547 · wf-form4_166612296659047.xml · nonDerivative · entry 1

Moftakhar Amir · CIK 0001884662 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 583,956

SEC source: 0001628280-22-026695 · wf-form4_166622972723633.xml · nonDerivative · entry 1

Moftakhar Amir · CIK 0001884662 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 567,236

F1 · kind: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSU's

SEC source: 0001628280-22-026698 · wf-form4_166622989830733.xml · nonDerivative · entry 2

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,625,277

F1 · kind: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSU's

SEC source: 0001628280-22-026698 · wf-form4_166622989830733.xml · nonDerivative · entry 1

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote.

Disclosed balance after: 2,453,439

F1 · kind: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSU's

F2 · ownership.direct: The shares are held directly by Julia Song. The reporting persons are husband and wife.

F2 · ownership.nature: The shares are held directly by Julia Song. The reporting persons are husband and wife.

SEC source: 0001628280-22-026696 · wf-form4_166622974761936.xml · nonDerivative · entry 4

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,381,859

F1 · shares: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSU's

SEC source: 0001628280-22-026696 · wf-form4_166622974761936.xml · nonDerivative · entry 3

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,401,257

F1 · shares: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSU's

SEC source: 0001628280-22-026696 · wf-form4_166622974761936.xml · nonDerivative · entry 2

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,420,655

F1 · shares: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSU's

SEC source: 0001628280-22-026696 · wf-form4_166622974761936.xml · nonDerivative · entry 1

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,434,914

F1 · shares: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSU's

SEC source: 0001628280-22-016183 · wf-form4_165428794923097.xml · nonDerivative · entry 1

Teamey Kyle · CIK 0001884670 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 29,486

F1 · shares: The reported shares are represented by restricted stock units, or RSUs, which vest on on the earlier of (i) June 1, 2023 or (ii) the day prior to the date of the Issuer's next annual meeting of stockholders.

SEC source: 0001628280-22-016182 · wf-form4_165428791125465.xml · nonDerivative · entry 1

Wilson Daryl C · CIK 0001884669 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 75,850

F1 · shares: The reported shares are represented by restricted stock units, or RSUs, which vest on on the earlier of (i) June 1, 2023 or (ii) the day prior to the date of the Issuer's next annual meeting of stockholders.

SEC source: 0001628280-22-016241 · wf-form4_165429743993706.xml · nonDerivative · entry 1

Gast Claudia · CIK 0001854131 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 59,694

F1 · shares: The reported shares are represented by restricted stock units, or RSUs, which vest on on the earlier of (i) June 1, 2023 or (ii) the day prior to the date of the Issuer's next annual meeting of stockholders.

SEC source: 0001628280-22-016173 · wf-form4_165428738332245.xml · nonDerivative · entry 1

WELLMAN ALEXI · CIK 0001705428 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 42,558

F1 · shares: The reported shares are represented by restricted stock units, or RSUs, which vest on on the earlier of (i) June 1, 2023 or (ii) the day prior to the date of the Issuer's next annual meeting of stockholders.

SEC source: 0001628280-22-016181 · wf-form4_165428788351444.xml · nonDerivative · entry 1

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 559,721

F1 · shares: The reported shares are represented by restricted stock units, or RSUs, which vest on on the earlier of (i) June 1, 2023 or (ii) the day prior to the date of the Issuer's next annual meeting of stockholders.

SEC source: 0001628280-22-016184 · wf-form4_165428797736803.xml · nonDerivative · entry 1

Garabedian Raffi · CIK 0001549086 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,354

F1 · shares: The reported shares are represented by restricted stock units, or RSUs, which vest on on the earlier of (i) June 1, 2023 or (ii) the day prior to the date of the Issuer's next annual meeting of stockholders.

SEC source: 0000899243-22-009227 · doc4.xml · nonDerivative · entry 1

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 530,235

F1 · price: The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $4.93 to $5.07, 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 purchased at each separate price.

F2 · balance_after: Reflects an increase of 16 shares pursuant to an adjustment of earnout shares reported on a Form 4 filed on November 12, 2021.

SEC source: 0000899243-22-007027 · doc4.xml · nonDerivative · entry 1

Gast Claudia · CIK 0001854131 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 30,208

F1 · shares: The shares are represented by restricted stock units, or RSUs, which vest in three equal annual installments beginning on February 17, 2023.

SEC source: 0000899243-22-007024 · doc4.xml · nonDerivative · entry 1

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 1,491,941

F1 · shares: The shares are represented by restricted stock units, or RSUs, which vest in 16 equal quarterly installments beginning on May 20, 2022.

SEC source: 0000899243-22-005508 · doc4.xml · nonDerivative · entry 1

Moftakhar Amir · CIK 0001884662 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 647,161

F1 · shares: The shares are represented by restricted stock units, or RSUs, which vest in 16 equal quarterly installments beginning on May 20, 2022.

F2 · balance_after: Reflects an increase of __ shares pursuant to an adjustment of earnout shares reported on a Form 4 filed on November 12, 2021.

SEC source: 0000899243-22-005509 · doc4.xml · nonDerivative · entry 1

Bodner Jeff · CIK 0001884665 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 54,900

F1 · shares: The shares are represented by restricted stock units, or RSUs, which vest as to one-fourth of the RSUs on May 20, 2022 and the remaining shares vest thereafter in 16 equal quarterly installments.

SEC source: 0000899243-22-005505 · doc4.xml · nonDerivative · entry 2

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 2,466,067

F1 · shares: The shares are represented by restricted stock units, or RSUs, which vest in 16 equal quarterly installments beginning on May 20, 2022.

F3 · balance_after: Reflects an increase of 73 shares pursuant to an adjustment of earnout shares reported on a Form 4 filed on November 12, 2021.

F4 · ownership.nature: The shares are held directly by Julia Song. The reporting persons are husband and wife.

SEC source: 0000899243-22-005505 · doc4.xml · nonDerivative · entry 1

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,641,617

F1 · shares: The shares are represented by restricted stock units, or RSUs, which vest in 16 equal quarterly installments beginning on May 20, 2022.

F2 · balance_after: Reflects an increase of 176 shares pursuant to an adjustment of earnout shares reported on a Form 4 filed on November 12, 2021.

SEC source: 0000899243-22-003141 · doc4.xml · nonDerivative · entry 1

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,373,083

F1 · kind: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.02 to $6.08, 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.

SEC source: 0000899243-22-003137 · doc4.xml · nonDerivative · entry 1

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 869,170

F1 · kind: The reported shares were sold to satisfy the reporting person's tax obligations in connection with the vesting of restricted stock units, or RSUs.

F2 · price: The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.02 to $6.08, 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.

SEC source: 0000899243-22-002456 · doc4.xml · nonDerivative · entry 1

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,374,425

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-22-002454 · doc4.xml · nonDerivative · entry 1

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 928,812

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-22-001172 · doc4.xml · nonDerivative · entry 1

Moftakhar Amir · CIK 0001884662 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 378,793

F1 · kind: The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of restricted stock units, or RSUs.

SEC source: 0000899243-22-001174 · doc4.xml · nonDerivative · entry 1

Bodner Jeff · CIK 0001884665 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 21,966

F1 · kind: The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of restricted stock units, or RSUs.

SEC source: 0000899243-22-001171 · doc4.xml · nonDerivative · entry 2

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 2,258,627

F1 · kind: The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of restricted stock units, or RSUs.

F2 · ownership.nature: The shares are held directly by Julia Song. The reporting persons are husband and wife.

SEC source: 0000899243-22-001171 · doc4.xml · nonDerivative · entry 1

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 5,371,491

F1 · kind: The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of restricted stock units, or RSUs.

SEC source: 0000899243-22-001167 · doc4.xml · nonDerivative · entry 1

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 840,781

F1 · kind: The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of restricted stock units, or RSUs.

SEC source: 0000899243-21-049175 · doc4.xml · nonDerivative · entry 1

Bodner Jeff · CIK 0001884665 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 26,191

F1 · shares: The shares are represented by restricted stock units, or RSUs, which vest as to one-fourth of the RSUs on May 20, 2022 and the remaining shares vest thereafter in 16 equal quarterly installments.

SEC source: 0000899243-21-049176 · doc4.xml · nonDerivative · entry 1

WELLMAN ALEXI · CIK 0001705428 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 13,072

F1 · shares: The shares are represented by restricted stock units, or RSUs, which vest in three equal annual installments beginning on October 12, 2022.

SEC source: 0000899243-21-049173 · doc4.xml · nonDerivative · entry 1

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 892,997

F1 · shares: The shares are represented by restricted stock units, or RSUs, of which one-fourth of the 457,763 RSUs vest on May 20, 2022 and the remaining shares vest thereafter in 16 equal quarterly installments and an additional 305,175 RSUs vest as follows: for any forty out of any 60 trading days during the five year period beginning on October 8, 2022 (i) 50% 0f the RSUs shall vest if the closing price per share of the Issuer's common stock is at or greater than $12.50 per share and (ii) 50% of the RSUs shall vest if the closing price is at or greater than $15.00 per share.

SEC source: 0000899243-21-045200 · doc4.xml · nonDerivative · entry 1

Moftakhar Amir · CIK 0001884662 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 416,614

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-21-045194 · doc4.xml · nonDerivative · entry 1

Bodner Jeff · CIK 0001884665 · Chief Accounting Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 11,191

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-21-045186 · doc4.xml · nonDerivative · entry 1

Wilson Daryl C · CIK 0001884669 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 46,364

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-21-045197 · doc4.xml · nonDerivative · entry 2

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 510,219

F4 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-21-045193 · doc4.xml · nonDerivative · entry 1

Garabedian Raffi · CIK 0001549086 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 24,868

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-21-045190 · doc4.xml · nonDerivative · entry 1

Dresselhuys Eric P. · CIK 0001571531 · Director · Chief Executive Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 130,059

F1 · shares: The shares are represented by restricted stock units, or RSUs, awarded upon the satisfaction of certain performance metrics as determined by the Compensation Committee. The RSUs were fully vested on the award date.

SEC source: 0000899243-21-044472 · doc4.xml · nonDerivative · entry 2

SOFTBANK GROUP CORP · CIK 0001065521 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 35,953,699

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein). Effective as of November 9, 2021, the reporting person was entitled to receive 4,204,936 shares of Issuer common stock pursuant to the Earnout Rights and 33,791 shares of Issuer common stock pursuant to the Expense Shortfall.

F3 · ownership.nature: These shares are held directly by SB Energy Global Holdings One Ltd. ("Holdings One"), a wholly owned subsidiary of SB Energy Global Holdings Limited, which is a wholly owned subsidiary of SoftBank Group Capital Ltd, which is a wholly owned subsidiary of SoftBank Group Corp. ("SoftBank"). SoftBank may be deemed to have voting and dispositive power with respect to the shares held by Holdings One.

SEC source: 0000899243-21-044472 · doc4.xml · nonDerivative · entry 1

SOFTBANK GROUP CORP · CIK 0001065521 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 35,919,908

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F3 · ownership.nature: These shares are held directly by SB Energy Global Holdings One Ltd. ("Holdings One"), a wholly owned subsidiary of SB Energy Global Holdings Limited, which is a wholly owned subsidiary of SoftBank Group Capital Ltd, which is a wholly owned subsidiary of SoftBank Group Corp. ("SoftBank"). SoftBank may be deemed to have voting and dispositive power with respect to the shares held by Holdings One.

SEC source: 0000899243-21-044446 · doc4.xml · nonDerivative · entry 1

Moftakhar Amir · CIK 0001884662 · Chief Financial Officer

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 315,588

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein). Effective as of November 9, 2021, the reporting person was entitled to receive 42,871 shares of Issuer common stock pursuant to the Earnout Rights and 345 shares of Issuer common stock pursuant to the Expense Shortfall.

SEC source: 0000899243-21-044443 · doc4.xml · nonDerivative · entry 2

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 2,221,405

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F4 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 301,769 shares of Issuer common stock pursuant to the Earnout Rights and 2,425 shares of Issuer common stock pursuant to the Expense Shortfall.

F5 · ownership.nature: The shares are held directly by Julia Song. The reporting persons are husband and wife.

SEC source: 0000899243-21-044443 · doc4.xml · nonDerivative · entry 1

Evans Craig E · CIK 0001885331 · Director · President

Song Julia · CIK 0001884681 · Chief Technology Officer

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 4,614,123

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F3 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 11,577 shares of Issuer common stock pursuant to the Earnout Rights and 93 shares of Issuer common stock pursuant to the Expense Shortfall.

SEC source: 0001104659-21-138309 · tm2132816-2_4seq1.xml · nonDerivative · entry 2

Breakthrough Energy Ventures, LLC · CIK 0001691687 · 10% owner

BREAKTHROUGH ENERGY INVESTMENTS LLC · CIK 0001888406 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 18,558,721

F3 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein). Effective as of November 9, 2021, the reporting person was entitled to receive and 20,096 shares of Issuer common stock pursuant to the Expense Shortfall.

F2 · shares: Each of these conditions was met as of November 9, 2021. Effective as of November 9, 2021, the reporting person was entitled to receive 2,500,751 shares of Issuer common stock pursuant to the Earnout Rights.

SEC source: 0001104659-21-138309 · tm2132816-2_4seq1.xml · nonDerivative · entry 1

Breakthrough Energy Ventures, LLC · CIK 0001691687 · 10% owner

BREAKTHROUGH ENERGY INVESTMENTS LLC · CIK 0001888406 · 10% owner

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

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 18,558,721

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00.

F2 · kind: Each of these conditions was met as of November 9, 2021. Effective as of November 9, 2021, the reporting person was entitled to receive 2,500,751 shares of Issuer common stock pursuant to the Earnout Rights.

F1 · shares: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00.

SEC source: 0000899243-21-044447 · doc4.xml · nonDerivative · entry 6

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 85,225

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F6 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 11,577 shares of Issuer common stock pursuant to the Earnout Rights and 93 shares of Issuer common stock pursuant to the Expense Shortfall.

F10 · ownership.nature: The shares are held of record by the Michael R. Niggli Jr. 2021 Gift Trust for which the reporting person serves as trustee.

SEC source: 0000899243-21-044447 · doc4.xml · nonDerivative · entry 5

NIGGLI MICHAEL R · CIK 0001377160 · Director

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 85,225

F1 · kind: Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc. (the "Issuer"), the reporting person is entitled to receive additional shares of Issuer common stock, for no additional consideration, if the volume weighted average price of Issuer common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the Issuer common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. Each of these conditions was met as of November 9, 2021.

F2 · kind: Following the closing of the merger, the Issuer determined that aggregate Transaction Expenses (as defined in the Merger Agreement) were lower than had been estimated at the time of closing. Pursuant to the Merger Agreement, this lower amount of Transaction Expenses resulted in an Expense Shortfall (as defined therein), which increased the Adjusted Equity Value (as defined therein).

F6 · shares: Effective as of November 9, 2021, the reporting person was entitled to receive 11,577 shares of Issuer common stock pursuant to the Earnout Rights and 93 shares of Issuer common stock pursuant to the Expense Shortfall.

F9 · ownership.nature: The shares are held of record by the Lorelei A. Niggli 2021 Gift Trust for which the reporting person serves as trustee.