12. Employee Benefit Plans

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2011 and 2021 Stock Option and Incentive Plan

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Stock-based compensation costs recognized, excluding the Company’s matching contributions of $1.9 million and $2.5 million to the Plug Power Inc. 401(k) Savings & Retirement Plan and quarterly Board compensation, were $10.7 million and $10.0 million during the three months ended June 30, 2026 and 2025, respectively. Stock-based compensation costs recognized, excluding the Company’s matching contributions of $4.8 million and $5.3 million to the Plug Power Inc. 401(k) Savings & Retirement Plan and quarterly Board compensation, were $21.8 million and $18.5 million during the six months ended June 30, 2026 and 2025, respectively. The methods and assumptions used in the determination of the fair value of stock-based awards are consistent with those described in our 2025 Form 10-K.

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The components and classification of stock-based compensation expense, excluding the Company’s matching contributions to the Plug Power Inc. 401(k) Savings & Retirement Plan and quarterly Board compensation, were as follows (in thousands):

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Service Stock Options Awards

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During the six months ended June 30, 2026, the Company granted 12,841,573 service stock option awards with a weighted average grant-date fair value of $1.94 per share and at a weighted average exercise price of $2.59. In addition, 701,254 service stock option awards were exercised at a weighted average exercise price of $2.33. Finally, 2,138,371 service stock option awards were forfeited at a weighted average exercise price of $6.75. The total fair value of the service stock option awards that vested during the six months ended June 30, 2026 and 2025 was approximately $2.9 million and $5.6 million, respectively.

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The Company estimates the fair value of its service stock options using a Black-Scholes valuation model, and the resulting fair value is recorded as compensation cost on a straight-line basis over the option vesting period. Key inputs and assumptions used to estimate the fair value of the service stock options include the grant price of the award, the expected

option term, volatility of the Company’s stock, and an appropriate risk-free rate. Estimates of fair value are not intended to predict actual future events or the value ultimately realized by employees who receive equity awards, and subsequent events are not indicative of the reasonableness of the original estimates of fair value made by the Company. The assumptions made for purposes of estimating fair value under the Black-Scholes model for the 12,841,573 service stock options granted during the six months ended June 30, 2026 were as follows:

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Compensation cost associated with service stock option awards represented approximately $6.2 million and $4.2 million of the total share-based payment expense recorded during the three months ended June 30, 2026 and 2025, respectively. Compensation cost associated with service stock option awards represented approximately $12.8 million and $7.7 million of the total share-based payment expense recorded during the six months ended June 30, 2026 and 2025, respectively. As of June 30, 2026, there was approximately $61.6 million of unrecognized compensation cost related to service stock option awards to be recognized over the weighted average remaining period of 2.30 years.

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Market Condition Stock Option Awards

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During the six months ended June 30, 2026, the Company did not grant market condition stock option awards. No market condition stock option awards were exercised during the six months ended June 30, 2026. Finally, 2,993,501 market condition stock option awards were forfeited at a weighted average exercise price of $13.39.

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Compensation cost associated with market condition stock option awards represented approximately $0.3 million and $1.4 million of the total share-based payment expense recorded during the three months ended June 30, 2026 and 2025, respectively. Compensation cost associated with market condition stock option awards represented approximately $0.9 million and $1.7 million of the total share-based payment expense recorded during the six months ended June 30, 2026 and 2025, respectively. Compensation costs associated with these awards are recognized as the requisite service period is rendered, regardless of when, if ever, the market condition is satisfied. As of June 30, 2026, there was approximately $0.1 million of unrecognized compensation cost related to market condition stock option awards to be recognized over the weighted average remaining period of 0.82 years.

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As of June 30, 2026, there were no unvested market condition stock option awards for which the employee requisite service period had not been rendered but were expected to vest.

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Restricted Stock and Restricted Stock Unit Awards

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During the six months ended June 30, 2026, the Company granted 1,928,776 restricted stock and restricted stock unit awards with a weighted average grant-date fair value of $2.59. In addition, 236,377 restricted stock and restricted stock unit awards were forfeited at a weighted average grant-date fair value of $4.77. The total fair value of the 182,730 restricted stock and restricted stock unit awards that vested during the six months ended June 30, 2026 and 2025 was approximately $0.7 million and $5.0 million, respectively.

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Compensation cost associated with restricted stock and restricted stock unit awards represented approximately $4.2 million and $4.4 million during the three months ended June 30, 2026 and 2025, respectively. Compensation cost associated with restricted stock and restricted stock unit awards represented approximately $8.2 million and $9.1 million during the six months ended June 30, 2026 and 2025, respectively. As of June 30, 2026, there was $21.1 million of unrecognized compensation cost related to restricted stock and restricted stock unit awards to be recognized over the weighted average period of 2.21 years.

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401(k) Savings & Retirement Plan

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The Company issued 1,971,338 and 4,223,083 shares of common stock pursuant to the Plug Power Inc. 401(k) Savings & Retirement Plan during the six months ended June 30, 2026 and 2025, respectively.

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The Company’s expense for this plan was approximately $1.9 million and $2.5 million during the three months ended June 30, 2026 and 2025, respectively. The Company’s expense for this plan was approximately $4.8 million and $5.3 million during the six months ended June 30, 2026 and 2025, respectively.

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Non-Employee Director Compensation

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The Company granted 76,100 and 256,345 shares of common stock to non-employee directors as compensation during the six months ended June 30, 2026 and 2025, respectively. All common stock issued is fully vested at the time of issuance and is valued at fair value on the date of issuance. The Company’s share-based compensation expense in connection with non-employee director compensation was approximately $0.1 million and $0.2 million during the three months ended June 30, 2026 and 2025, respectively. The Company’s share-based compensation expense in connection with non-employee director compensation was approximately $0.2 million and $0.4 million during the six months ended June 30, 2026 and 2025, respectively.

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During the six months ended June 30, 2026, non-employee directors were also granted 163,638 service stock option awards and 159,730 common stock options that vest over a one and three year period, respectively, with the 163,638 service stock option awards included within the total 12,841,573 service stock option awards disclosed above. The Company’s share-based compensation expense in connection with these awards was approximately $0.1 million during the six months ended June 30, 2026. Additionally, in accordance with the non-employee director compensation plan, during the six months ended June 30, 2026 and 2025, the Company reimbursed $0 and $0.1 million of administrative expenses incurred by non-employee directors, respectively.