16.Stock-Based Compensation

Option Plan

In 2020, the Company established the 2020 Unit Option Plan (the “Option Plan”) under which employees, directors, and consultants were originally granted non-qualified options to purchase Class A-1 units of Fluence Energy, LLC. As of September 30, 2021, the Company determined that achievement of the performance conditions related to awards granted under the Option Plan was not probable and therefore, no expense was recognized for the non-qualified options during the fiscal year ended September 30, 2021. The completion of the initial public offering on November 1, 2021 (the “IPO”) resulted in achievement of the performance condition for the majority of the underlying awards granted under the Option Plan. In connection with the IPO, the non-qualified options were converted into non-qualified stock options to purchase shares of Class A common stock of Fluence Energy, Inc. Non-qualified stock options under the Option Plan have a contractual term of ten years from the date of grant and an exercise price of $2.45. The Company estimated the fair value of the awards using the Black-Scholes option-pricing model. The outstanding awards continue to be governed by the Option Plan. The Option Plan is accounted for as an equity plan. The Company will not make any further awards under the Option Plan.

As of March 31, 2026, 1,397,309 stock options under the Option Plan remain outstanding with no unrecognized stock compensation expense.

2021 Incentive Award Plan

During the fiscal year ended September 30, 2021, the Company established the 2021 Incentive Award Plan (the “2021 Incentive Plan”) which reserved 9,500,000 shares of Class A common stock of Fluence Energy, Inc. for issuance to management, other employees, consultants, and board members of the Company. On March 12, 2026, at the 2026 annual meeting of stockholders of the Company, the stockholders approved the amended and restated 2021 Incentive Award Plan (the “A&R Incentive Plan”), which increased the number of shares of Class A common stock authorized for issuance thereunder by an additional 6,700,000 shares. The A&R Incentive Plan governs both equity-based and cash-based awards, including incentive stock options, non-qualified stock options, restricted stock, PSUs, and RSUs. Stock-based awards currently issued pursuant to the A&R Incentive Plan that are expected to be settled by issuing shares of Class A common stock are recorded as equity awards. The Company accounts for forfeitures as they occur.

Restricted Stock Units

RSUs granted under the A&R Incentive Plan vest ratably at one-third annually on the anniversary of the grant date over a three-year period pursuant to the terms of their applicable award agreements. The Company generally expenses the grant date fair value of the awards on a straight-line basis over each of the three separately vesting tranches within a given grant. There is no contractual term on the RSUs granted under the A&R Incentive Plan. The Company estimated the fair value of the awards using the market value of our Class A common stock on the grant date. The market value of our Class A common stock is calculated using the closing price of our Class A common stock on the date of grant. The following table summarizes activity under the A&R Incentive Plan for the six months ended March 31, 2026:

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As of March 31, 2026, 1,769,760 RSUs previously issued remained outstanding with unrecognized stock compensation expense of $16.8 million.

Non-Qualified Stock Options

During the six months ended March 31, 2026, there were 230,440 non-qualified stock options granted, exercisable for Class A common stock under the A&R Incentive Plan. Non-qualified stock options under the A&R Incentive Plan have a contractual term of ten years from the date of grant. The Company estimated the fair value of the awards using the Black-Scholes option-pricing model. The non-qualified stock options granted under the A&R Incentive Plan vest ratably at one-third annually on the anniversary of the grant date over a three-year period pursuant to the terms of their applicable award agreements. The Company generally expenses the grant date fair value of the awards on a straight-line basis over each of the three separately vesting tranches within a given grant. As of March 31, 2026, 657,313 non-qualified stock options previously issued pursuant to the A&R Incentive Plan remained outstanding with unrecognized stock compensation expense of $4.9 million.

Performance Share Units

During the six months ended March 31, 2026, the Company granted 511,997 PSUs settleable in Class A common stock under the A&R Incentive Plan. The Company has two rounds of PSU grants under the A&R Incentive Plan outstanding, the first commencing at the start of fiscal year 2025 and the second commencing at the start of fiscal year 2026. The PSUs for the 2025-2027 performance cycle and the 2026-2028 performance cycle are both earned based on (i) the achievement of two financial performance metrics: cumulative Adjusted EBITDA (65% weight) and cumulative revenue (35% weight), over a two-year performance period beginning October 1st in the year of grant through September 30th in the second year after grant, and (ii) service-based vesting based on continued employment from the date of grant through September 30th in the third year after grant. The performance targets for cumulative revenue and cumulative Adjusted EBITDA are set by the Company’s Board of Directors and the Board’s Compensation and Human Resources Committee. PSUs are considered fully vested when both the performance and service based requirements are met in accordance with the vesting requirements and will be settled in Class A common stock no more than 60 days after the end of the third fiscal year. The awards can be paid out in a range of 50% to 200%, with 0% paid out for below-threshold performance, based on the achievement of the performance criteria and upon continued service through the performance period. The Company estimated the fair value of the awards using the market value of our Class A common stock. The market value is calculated using the closing price of our Class A common stock on the date of grant. The Company monitors the achievement of the performance criteria and expenses ratably the grant date fair value of the awards probable to vest over the requisite service period. If there are changes to the amount of probable awards to vest based on achievement of performance criteria, the related stock-based compensation expense may be significantly increased or reduced in the period that our estimate changes.

As of March 31, 2026, 979,132 PSUs previously issued remained outstanding with estimated unrecognized stock compensation expense of $8.4 million.

Other

In connection with the acquisition of Nispera AG in 2022, Fluence issued 531,202 shares of restricted stock to Nispera’s management team. The estimated post combination expense to the Company as a result of the business combination was approximately $6.9 million which was being recognized on a straight-line basis over the remaining service period that was stipulated in each holder’s original restricted stock agreement. As of March 31, 2026, no restricted stock awards previously issued remained outstanding with and there is no unrecognized stock compensation expense.

Stock-based compensation expense

Stock-based compensation expense was recorded as follows:

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